We've come a long way since the only tools we had to address this were the Bible, manuscripts copied by generations of monks from the Greco-Roman era, and letters from world travelers.
New World Prehistory
Arctic Genetic Prehistory
Some of the most definitive answers about the prehistory of the Americas came in an analysis of ancient DNA and modern population genetics released a couple of weeks ago. This study established that:
1. The Saqqaq and Dorest Paleo-Eskimo populations were a single, closely genetically related migration wave, that arrived in Arctic North America around 3500 BCE and persisted until about 500 CE, despite the marked break in archaeological culture between the sequential populations. These Paleo-Eskimos had surprisingly little genetic admixture with either pre-existing Native American populations, or with the proto-Inuits who ultimately replaced them in the Arctic - consistent with Inuit legends describing a distinct arctic people who kept themselves separate from other peoples
2. The 6th to 7th century CE Berginian Birnirk culture (in turn derived from Siberian populations) is the source of the proto-Inuit Thule people, who were the last substantial and sustained pre-Columbian peoples to migrate to the Americas.
3. "Although we cannot preclude later gene flow between the Dorset and the Thule (that is, subsequent to the more ancient gene flow that occurred at least 4000 years ago), the contrasting genetic and cultural affinities of the Sadlermiut individuals present a conundrum. This culture that went extinct in 1903 CE from European disease has long been considered Thule-acculturated Dorset people, likely due to intermarriage; however, genetic evidence from this study suggests that they were Thule people who had somehow acquired Dorset stone technology."
The Na-Dene people
The Na-Dene people (aka Athapaskans) do not have significant Paleo-Eskimo admixture. This can be added to some other notable data points in the existing literature about the Na-Dene:
* Genetic and linguistic evidence establish that the Na-Dene people are distinct not only from Paleo-Eskimos and the Inuit, but also from other Native Americans. While the Na-Dene are heavily admixed with pre-existing Native American populations, there are genetic indicators of a wave of Na-Dene migration long after the original peopling of the Americas by modern humans ca. 15,000-18,000 years ago. About 10% of Na-Dene ancestry is distinct from the initial founding population of the Americas. The Na-Dene, like Inuits, have Y-DNA haplogroups that are specific to them and of more recent origin that the founding Y-DNA haplogroups of the Americas.
* Linguistic evidence establishes that the Na-Dene people's expansion is North America originated in Western Alaska and moved east from there to the rest of Alaska, Western Canada, and the Pacific Northwest.
* The earliest archaeological evidence of Na-Dene people in Alaska comes from the general vicinity of Wrangell-St. Elias National Park in Southern Alaska around 1500 BCE although arguably they were present in the Southwestern Yukon in Canada as early as 2500 BCE.
* The Na-Dene languages are related to the Yenesian languages of the Ket people of Siberia, a Paleo-Siberian population that was exiled from general vicinity of the Altai Mountain region of Southern Siberia to Siberia's Yenesian River area around 0 CE, according to the oral histories of the Ket people. The strength of the linguistic connection is consistent with a divergence of the two language families from a common origin around 3500-4000 years ago, a similar time depth, for example, to the division between Latin and Gaelic in the Indo-European language family.
* Substantial admixture with local populations by both the Ket people and that Na-Dene people, however, has obscured any common genetic linkages of these peoples, which would already have been difficult to detect using the crude 1993 genetic tests of the Ket people applied to a small sample that was used to make the comparison.
* The Na-Dene people migrated in two parallel waves from different parts of Western Canada to the American Southwest around 1000 CE. Their descendants are the Apache and Navajo tribes.
Other New World Contacts
* Around 1000 CE, Lief Erickson led a small population of Vikings to a short lived agricultural settlement called Vinland in maritime Canada. Recent discoveries announced in National Geographic in November of 2012 established that there were trade relations between the Vikings and indigeneous Arctic people at around the same time at the Northern tip of Canada's Baffin Island.
* From around 900 CE to 1100 CE, the "people who lived more than 1,000 years ago in what today is the Lambayeque region, about 800 kilometers (500 miles) north of Lima, had genetic links to the contemporaneous populations of Ecuador, Colombia, Siberia, Taiwan and to the Ainu people of northern Japan." These people were practitioners of the Middle Sican culture, a cultural renaissance in the region marked by veneration of "Sican diety" and "Sican lord" with vaguely Asian eyes in material cultural items including pottery and metalwork, who reputedly came to them from across the ocean via a balsa wood raft. (Earlier ancient mtDNA work here and here). A few hundred years later, however, the Sican diety cult abated.
Sicán iconography is dominated by the Sican Deity. It decorates all artistic media of the Sicán, including ceramics, metal works, and textiles. The icon is most commonly represented with a mask face and upturned eyes. Sometimes it may be shown with avian features, such as beaks, wings, and talons, which are evident in Early Sicán ceramics. These avian features are related to Naylamp, the key figure in Sicán mythology. Naylamp was said to be the founder of the first dynasty of prehistoric kings in La Leche and Lambayeque valleys. In The Legend of Naylamp, first recorded in the 16th century by the Spanish chronicler Miguel Cabello de Balboa, Naylamp is said to have traveled on a balsa raft by sea to the Lambayeque shores. He founded a large city, and the 12 sons of his eldest son each founded a new city in the Lambayeque region. When Naylamp died, he sprouted wings and flew off to another world (Nickle Arts Museum 2006, p. 18 and 65).* Late in the period of Austronesian expansion (probably not earlier than 700 CE, with radiocarbon dated examples found in the Cook Islands by 1000 CE), perhaps from a final launching point at Easter Island, the kumara, a yam-like plant native to South America and possibly native to Peru, entered Austronesian territory and became a staple food. But, no genetic traces of the New World are found in Austronesian populations. It is possible that the kumara's arrival in Oceania and the Asian genetic influences found in Middle Sican graves involved the same instance of cultural Old World-New World contact.
The First Americans
* The remaining peoples of the Americas, with a quite small founding population, crossed the Berginian land bridge from Northeast Asia, were bottled up there cutoff by cold and glaciers from both Asia and the rest of North America, and then migrated to the rest of the Americas once the glaciers subsided enough to allow them to pass to the rest of the continent. One group took a Pacific coastal route that reached South America within about a thousand years. The other made their way to eastern North America and moved Westward starting around the time of the emergence of the Clovis culture.
Some investigators, such as those conducting a 2013 mtDNA analysis have argued that the Indigeneous peoples of South America have only a subset of the first Americans whose full range of Y-DNA and mtDNA diversity is preserved only in North America and is attributable to a wave of inland migration limited to North America. In particular, they see mtDNA X2a and C4c as markers of this migration. This areal distinction predates and is not difference between Na-Dene and non-Na-Dene people, and instead derived from local Na-Dene admixture with other Native American populations. High coverage autosomal data in a 2013 study do show some North-South cline in the Americas, but not a lot of distinct population structure.
In contrast, a 2007 paper argued instead that there was no population genetic structure in the founding population of the Americas, at least at the major mtDNA clade level.  A 2004 Y-DNA analysis came to a similar conclusion. It is not clear if apparent differences in diversity are a serial founder effect, or if the greater genetic diversity in North American Native Americans reflects a Beringian population that he some population structure consisting of at least two distinct peoples when the path from Beringia to North America opened up, or if apparent structure is simply illusory.
* The first Americans brought dogs, but not horses, and were hunter-gatherers. Mega-fauna extinction across the Americas followed their arrival.
* These peoples were isolated from the Old World's modern humans for the next 10,000 years or so in Northern North America and the next 12,500 years or more in South America.
* There are isolated instances where the evidence seems to point to the existence a pre-Last Glacial Maximum modern human population in the Americas perhaps as old as 25,000 years ago on the eastern coast of the Americas, e.g. in Virginia and Brazil. The evidence is disputed and the wider impact, ecological or cultural, or genetic appears to have been negligible.
* The time depth of Amerind proto-languages, if any, is too great to demonstrate the connection of Amerind languages into a macro-language family. Linguistic drift has left Amerind languages with every possible combination of language features.
* While up to six pre-Columbian waves of Old World contact have impacted Canada and Alaska, and as many as three have impacted the remainder of North America, just two or three have had an impact on Latin America in pre-Columbian times, and all but one of those contacts was pretty much restricted to Peru.
New World Redux
This is a fairly comprehensive account of the pre-Columbian contacts between the New World and Old World. We also have a much more detailed since of the greater historical trends within the New World.
Pieces are also coming together in Europe.
First Wave Farmers
Ancient DNA evidence reveals that the first wave of farmers and herders to arrive in Europe both in Central Europe and on the Southern European coast, were predominantly Y-DNA G2a and F with some Y-DNA I1 and I2, and carried the same highly diverse suite of mtDNA types.
This was assembled into a coherent genetic population by the 5000s BCE that sharply contrasts with the Mesolithic hunter-gather population of Europe dominated by Y-DNA I2 and mtDNA U5b. The first wave of farmers probably brought about the demise of all of the languages of Europe's Mesolithic hunter-gathers and dramatically reduced their contribution to the European gene pool. The hunter-gather populations and farmer populations show little admixture with each other in the early period, although admixture with hunter-gatherer women is greater towards the LBK frontier in north central Europe. Populations that were side by side geographically maintained genetic distinctions between hunter-gatherers and farmers for at least a thousand years.
Y-DNA I1, which is now most common in Scandinavia, apparently arose not locally, but as part of the five wave Neolithic population assembled in Hungary or further to the Southwest, that died out elsewhere but thrived in Scandinavia due to serial founder effects.
The first wave of farmers and herders to arrive in Europe give rise to an intense population boom, almost universally followed a few centuries later, by a dramatic population bust. In some places, the population reverted to hunting and gathering, while in others, farming and herding remained the main means of food production, but populations fell although not to hunting and gathering levels.
Early Neolithic and Bronze Age Crete
Ultimately, the package of crops and technologies that produced the Neolithic revolution in Europe were derived from a package assembled mostly in the Fertile Crescent of SW Asia. A small sample of 15 ancient mtDNA samples from 8000 BCE in the Fertile Crescent Neolithic favors a maritime migration route of first wave farmers into Europe via Cyprus, Crete and the Aegean, rather than via Anatolia.
A different Bronze Age Minoan mtDNA sample (N=37), five thousand years later, however, mostly by virtue of being so rich in mtDNA haplogroup H, more closely resembles second wave farming populations of Bronze Age Europe (as well and a particular affinity to Northern and Western European populations, as well as to modern Kurdish populations) than first wave Neolithic populations, and is also almost identical to the current population of the part of Crete from which the ancient DNA samples were obtained, a modern population also rich in a European clade of Y-DNA R1b.
The Caucasus And The Vicinity In The Copper Age
The first farmers were most similar genetically to the peoples of the Caucasus mountains and Northern Anatolia today, although the population genetic landscape of Europe would have been different then.
This could mean that the first farmers originated in the Caucasus mountains, but could also simply mean that the Caucasus and a few other European populations like the Sardinians, are relict populations that escaped the genetic transformations of the next wave of metal using farmers that followed the initial Neolithic population bust in Europe due to their isolation and distinct climate niches.
A critical moment in the history of the Caucasus region was the Maikop culture (3700 BCE to 3000 BCE) of the Northern Caucasus which was an instrumental influence in early metallurgy development that spread to the contemporaneous and neighboring Yamna culture of the Pontic Steppe which is in the Kurgan hypothesis proto-Indo-European (the Maikop people possibly also spread metallurgy technology to other early adopters of metal age technology such as the Bell Beaker people). The Maikop culture also appears to have been the first to adopt the Kurgan burial practices that subsequently came to be a litmus tests for early Indo-European cultures before they adopted cremation on a widespread basis sometime around 2000 BCE or earlier.
There does not appear to be any archaeological evidence to support the claim that the Maikop culture was derived from and strongly influenced by the contemporaneous Uruk culture of the Sumerians of Mesopotamia, which instead arose independently of the Sumerians or the Balkan-Anatolian copper age, with influences mostly from Iran and South Central Asia. But, there is evidence to support the claim that there were trade ties (or more) between the Kura-Araxes culture of the Southern Caucasus (i.e. the modern Republic of Georgia) and adjacent parts of Iran and Eastern Anatolia did have longstanding and sustained ties to this Sumerian Uruk culture.
The Population Genetic Impact of Metal Age Second Wave Farmers
Sometime between the population bottleneck followed by the collapse of the first wave Neolithic in Europe and the end of the Bronze Age, there was a second major shift in European population genetics that caused Western and Northern Europe to be dominated by Y-DNA R1b, caused Central and Eastern Europe to be dominated by Y-DNA R1a, introduced Y-DNA E and J to Europe, and caused mtDNA to become the predominant mtDNA type across Europe.
Since the origins of Y-DNA R1b (West Asia), E (North and East Africa), J2 (West Asia) ad J1 (SW Asia) (with the transition from J2 to J1 being somewhat clinal) are so different geographically, they may have arrived in separate migration waves in this time period, and both E and J could be somewhat later arrivals (for the most part) than R1a and R1b in areas where R1a and/or R1b are predominant singly or in combination.
In Central and Eastern Europe, this genetic transition generally attributed to Indo-Europeans particularly in the Corded Ware culture (ca. 2900 BCE to 2400 BCE), a metal using culture fairly directly emerging from the Indo-European urheimat. Ancient DNA evidence reported in a newly announced conference paper confirms this analysis:
To understand the population transformations that took place in Europe since the early Neolithic, we used . . . DNA from a number of different archaeological cultures of central Europe (Germany and Hungary). The samples spanned the time period from 7,500 BP to 3,500 BP (Early Neolithic to Early Bronze Age periods) and most of them were previously studied using mtDNA (Brandt, Haak et al., Science, 2013). . . . By analyzing this data together with a dataset of 2,345 present-day humans and other published ancient genomes, we show that late Neolithic inhabitants of central Europe belonging to the Corded Ware culture were not a continuation of the earlier occupants of the region. Our results highlight the importance of migration and major population turnover in Europe long after the arrival of farming.The Corded Ware culture is also a likely principle source of one of the three main autosomal genetic ancestry components in Europe - "Ancestral Northern Europeans (ANE)" ("In Europe today it peaks among Estonians at just over 18%, and, intriguingly, reaches a similar level among Scots. However, numbers weren't given for Finns, Russians and Mordovians, who, according to one of the maps, also carry very high ANE, but their results are confounded by more recent Siberian admixture"), which together with Western European Hunter-Gatherers (WHG) from Mesolithic Western Europe ("today the WHG component peaks among Estonians and Lithuanians, in the East Baltic region, at almost 50%"), and Early European Farmers (EEF) ("today peaks at just over 80% among Sardinians. Apart from the Stuttgart sample, the EEF meta-population includes Oetzi the Iceman and a Neolithic Funnelbeaker farmer from Sweden."), contribute most of Europe's population genetic ancestry.
There are two groups of significant outliers to this model, however (from the same link) (which also does not seem to include any Roma populations with affinities to South Asia or more recent immigrant populations):
While our three-way mixture model fits the data for most European populations, two sets of populations are poor fits.
First, Sicilians, Maltese, and Ashkenazi Jews have EEF estimates beyond the 0-100% interval and they cannot be jointly fit with other Europeans. These populations may have more Near Eastern ancestry than can be explained via EEF admixture, an inference that is also suggested by the fact that they fall in the gap between European and Near Eastern populations in the PCA of Fig. 1B.In Western Europe, the source of this genetic transformation is less clear. The Bell Beaker culture (ca. 2800 BCE to 1800 BCE) and its successors prior to Bronze Age collapse (see below) is in roughly the right places at the right time, but was not commonly been associated with mass demic transformation in academic circles in the last 20th century and the early 21st century before ancient DNA samples suggested otherwise over the last decade or so. However, it also isn't clear at all what the genetic make up of Atlantic Neolithic megalithic culture peoples was like before Bell Beaker cultures appeared.
Second, we observe that Finns, Mordovians, Russians, Chuvash, and Saami from northeastern Europe do not fit our model. To better understand this, for each West Eurasian population in turn we plotted f4(X, Bedouin2; Han, Mbuti) against f4(X, Bedouin2; MA1, Mbuti), using statistics that measure the degree of a European population’s allele sharing with Han Chinese or MA1. Europeans fall along a line of slope >1 in the plot of these two statistics. However, northeastern Europeans fall away from this line in the direction of Han. This is consistent with Siberian gene flow into some northeastern Europeans after the initial ANE admixture, and may be related to the fact that Y-chromosome haplogroup N is shared between Siberian and northeastern Europeans but not with western Europeans. There may in fact be multiple layers of Siberian gene flow into northeastern Europe after the initial ANE gene flow, as our analyses . . . show that some Mordovians, Russians and Chuvash have Siberian-related admixture that is significantly more recent than that in Finns.
The Bell Beaker culture and its successors in continuity with it, which was probably Vasconic (i.e. linguistically related to Basque) rather than Indo-European linguistically, expanded across a generally Western and Northern European territory and held off Indo-Europeans associated with the Corded Ware culture and related archaeological cultures for a thousand years along a fairly static border that still biogeographically divides Western Europe from Eastern Europe.
The Bell Beaker culture expanded out of Southern Portugal across Europe. But, the origins of the Bell Beaker culture prior to its expansion out of Portugal are unclear. Indigenous origins, origins in Western Sahara, and origins in Bohemia and more remotely in the Caucasus Mountains, have been suggested.
By the time the Iron Age arrived following Bronze Age collapse ca. 1200 BCE, the population genetics of Europe were generally similar to those today prior to historic era migrations. Indo-Europeans came to linguistically and culturally dominate the formerly Bell Beaker territory around this time, but seem to have had quite a modest population genetic impact.
The Urnfield Culture ca. 1300 BCE, in the region shown on the map below, via Wikipedia, which may have been linguistically proto-Celtic, was probably one of the first Indo-European cultures in Western Europe.
Y-DNA E and J in Europe
Y-DNA E has a split distribution, with Y-DNA E clades in SW Europe probably arriving from NW Africa, and SE Europe probably receiving its Y-DNA E clades from NE Africa in parallel but separate migration waves, quite likely by sea.
Y-DNA J2 appears to have spread largely by maritime travel also along the Southern European coast, possibly mixed with a minority of Y-DNA J1, with a significant subset of both J2 and J1 due to the Jewish diaspora and migration (and probably due to Phoenicians before that). J2 is much more common than J1 in Europe, indicating a predominantly West Asian origin, rather than a Semitic one. The J2 and J1 divide can also be conceptualized as a divide between high country J2 populations and lowland J1 populations.
The low levels of Y-DNA J and E in most of Europe, and their relatively late arrival, also disfavor any theory that there were substantial areas where Afro-Asiatic languages were spoken in Europe in unattested prehistory. Historic migrations of Hebrew speaking Jews, Phoenicians, Arabs/Moors, North African Romans, and Egyptians are sufficient to account for all Afro-Asiatic linguistic influences in Europe and their histories are older than almost any other part of the world.
The scarcity of Y-DNA J and G in the Basque population tends to disfavor of Middle Eastern or West Asian origin for their Y-DNA R1b carrying patriline ancestors. But, genetic diversity of R1b supports an origin for the haplogroup in the East of Europe and Central Asia, rather than in Western Europe as an indigenous Y-DNA type there.
The lack of Y-DNA R1b in Western Sahara apart from Chadic R1b-V88 which is very distinct from European Y-DNA R1b, the absence of any evidence of pre-Phoenician Afro-Asiatic linguistics in the Bell Beaker area (or any evidence of Semitic languages away from coastal areas), the lack of a strong metal processing tradition in copper age Western Sahara all point away from Bell Beaker origins there in my humble opinion.
Y-DNA H in Europe
Y-DNA H, which is common in South Asia, is found in Europe is due almost entirely to historic era Roma (aka Gypsy) migrations in the current era.
The Uralic Langauges In Europe
The timing and manner by which Uralic languages arrived in Finland, Karelia, and the Baltic area around the time of the Finnish Bronze Age ca. 1500 BCE (after about 1000 years as a linguistically Indo-European region that was part of the Corded Ware culture) is increasingly clear. Not surprisingly, given their linguistic distinctiveness and position near the Eurasian boundary, a population genetic study of 6,209 contemporary Europeans targeted at identifying fine scale structure in European populations found that:
[T]he Finns are the most differentiated from the rest of Europe (as might be expected); [there is] a clear divide between Sweden/Norway and the rest of Europe (including Denmark); and an obvious distinction between southern and northern Europe. We also observe considerable structure within countries on a hitherto unseen fine-scale - for example genetically distinct groups are detected along the coast of Norway.
The events giving rise to the Uralic Hungarian language in the historic era by a narrow Magyar elite are also now well understood.
Footnote On European Linguistics In Light Of Genetics
There are lots of scholars who have argued for an early appearance of Indo-European languages in Europe. I've seen it argued that the Mesolithic hunter-gatherers of Atlantic and Baltic coasts spoke Indo-European languages, that the people who kept Venus figurines spoke Indo-European languages, that the LBK and Cardial Pottery Neolithic people spoke Indo-European languages, that the Bell Beaker people spoke Indo-European languages, that the Minoans spoke Indo-European languages, and that the pre-Hittite people of Anatolia mostly spoke Indo-European languages.
Personally, I find these assertions to be highly implausible. Proto-Indo-European probably dates to around 4000-4500 BCE and was probably a minor language family of Central Asia and Eastern Europe with a narrow geographic scope until around 2000 BCE when it exploded across Europe, West Asia, South Asia, Central Asia and Siberia, expanding further at the end of the Bronze Age into Western Europe.
In Greece, we don't know much about the Minoan language, but we know enough from Egyptian phonetic translations of Minoan prayers/spells/songs and from correspondences between Linear A and Linear B, that Minoan was not an Indo-European language and bore some resemblance to the Hattic language spoken in Anatolia at the same time that Minoan palace culture thrived. We know the the Mycenean Greeks spoke an early version of ancient Indo-European Greek, and that before conquering the Minoans who had a written language, that they conquerered pre-Mycenean people of mainland Greece (the Pelopenese) around 2000 BCE, and that they were people who had a greater cultural affinity to the Greeks and hence probably spoke a non-Indo-European language. We also have substantial evidence of a strong non-Indo-European substrate influence in ancient (and modern) Greek.
We know that the Hattic language of much of Anatolia subsequently conquered by the Indo-European Hittites, which is attested in Hittite writings as a liturgical language, was non-Indo-European. Most of the Indo-European languages of Anatolia are attested only after the fall of the Hittite empire around 1200 BCE. We know from contemporary correspondence from Mesopotamian trading posts that the Hittite empire was just a tiny two town confederation around 2000 BCE.
We know that to the South and West of Anatolia, neither the Sumerian language, nor the kindred Kassite language, nor the Akkadian language that replaced the Sumerian language, nor the Coptic language spoke in Egypt, or the Phoenician language spoken by Eastern Mediterranean maritime traders who emerged out of Lebanon, were Indo-European.
We know that the Indo-Aryan Mittani language first appeared on the scene near the modern Turkish-Iranian border around 1500 BCE which was about 500 years after the archaeologically attested appearance of the Sanskrit speaking Aryan people in South Asia, and that the Indo-Iranian languages appeared in Persia around the same time (2000 BCE); these languages share a common origin around 2000 BCE. There is no positive evidence of any kind to support the argument that the Harappan language was an Indo-European language and there were no Indo-European languages spoken in South Asia or Iran that were not Indo-Iranian or Indo-Aryan until Hellanic Alexander the Great imposed Greek upon Persia ca. 300 BCE. Sanskrit also shows substrate influences not shared by other Indo-European languages again arguing for a non-Indo-European Harappan language. There is evidence that at least two non-Indo-European languages (Elamite and a newly discovered unnamed language in an Hittite era historical record) were spoken in Iran as late of the Iron Age (both of these language died in the historic era).
We know that the Basque people, who have typically Western European high levels of Y-DNA R1b and mtDNA H, preceded Indo-European language speakers in the area and never underwent the language shift seen by other peoples (nature's secret weapon by have related to rh blood type factors that reduced the viability of the pregnancies of local women with would be conquering men, in addition to a secure and remote mountainous environment to serve as a refugium that could be bypassed by subsequent Indo-European conquerors). We also know that linguistically Vasconic people were present in a larger geographic area in pre-Roman times, that a large swath of formerly Bell Beaker Europe has Vasconic place names, that there are traces of Vasconic substrate influences in the Indo-European languages of Western Europe (for example, base twenty numbers), and that the archaeological appearance with cultural traits that were litmus tests for Bronze Age Indo-Europeans like cremation, and Celtic material culture didn't start to appear in the archaeological record until about 1300 BCE in France and Spain and Italy. And, we know that this later wave of people in Western Europe didn't have much of a demic impact, suggesting something less than a blowout in terms of comparative technological and cultural superiority. We know that the megalithic culture of Western Europe was pre-Celtic.
Litmus tests for Indo-Europeans appear in proto-Germanic territory only around the Nordic Bronze Age (ca. 1500 BCE) and arguably only in the later part of the Nordic Bronze Age (ca. 1200 BCE).
We know that linguistically non-Indo-European Etruscans were present in Tuscany prior to the formation of the Roman state in the iron age, and persisted into the current era, although they may not have preceded the Italic peoples by much more than a century or two, and probably shared a language family with the linguistically non-Indo-European Rhaetic people of Alps to the North.
We know that there were other small pockets of linguistically non-Indo-European between Italy and Anatolia into the attested Roman era.
We know that the Slavic languages expanded starting around 400 CE or later, although our knowledge of what was spoken before the Slavic languages in the area into which they expanded is less solid.
There is no evidence that Indo-European languages were spoken on the North African coast prior to the expansions of Greek and Roman civilizations into those areas in the Iron Age.
We know that the linguistically Indo-European Tocharians arrive in the Tarim Basin around 2000 BCE, although they would have had to commence their expansion from an Indo-European urheimat before then. By all accounts this is the furthest eastern outpost of Indo-European languages and involved people who physically and culturally had much in common with Indo-European language speakers further west.
There is a very plausible argument to suggest that the Finns converted to an Indo-European language around 2500 BCE, only to adopt the non-Indo-European Finnish language around the time of the Finnish Bronze Age ca. 1500 BCE.
There are historically attested and linguistic reasons to suspect that the Armenian language did not come into being until after the fall of the Hittite empire.
There is good reason to doubt linguistic chronologies pointing towards an early Neolithic Anatolian origin of the Indo-European languages, both in terms of a methodology that ignores that fact that language change is heightened in the formative years of a language rather than drifting at an even rate due to a desire to be distinct from prior languages and due to substrate influences as language shift takes place. Ignoring these factors makes a language seem artificially long. The available evidence on the pre-Hittite linguistic state of Anatolia also tends to contradict the Anatolian theory.
The Kurgan theory provides plausible cultural antecedents for the Indo-European languages outside of Anatolia that are not rebutted by contradictory evidence and that are bolstered by the distribution of Y-DNA R1a which is found in ancient DNA samples from some of the oldest known Indo-European language speakers such as the Tocharian mummies and late Corded Ware peoples. The low levels of Y-DNA R1a in Western Europe also tends to disfavor the notion that second wave early metal age farmers in these regions were Indo-European linguistically.
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This post was last updated September 11, 2014.