For full disclosure, I note than I am 50% Swede-Finn (my Lutheran Swede-Finn ancestors, who are on my maternal side, migrated to the Upper Peninsula of Michigan in the late 1800s), and it is possible that my account may be influenced by this fact. Some key points (with some of my own additions):
Finland was repopulated after the Last Glacial Maximum (which covered all of Northern Eurasia in an ice sheet ca. 20,000 BCE and completely ended modern human and any other hominin population of this region) only around 9,000 BCE (some sources indicate a date closer to 7300 BCE which would be about 9300 BP which could be caused by misunderstandings regarding the units in which dates are quoted), in an era sometimes called the Mesolithic or Epipaleolithic era.
Mesolithic Finnish Genetics
Uniparental genetics suggest that the source population for the original resettlement, which has left a strong serial founder effect impact on the Saami population (albeit with strong Uralic contributions) made its way up the Atlantic Coast (e.g. the Dutch and Belgian coast), probably from a Franco-Cantabrian refugium which also contributed to the proto-Berber populations with which it shares two of its three predominant mtDNA haplogroups, in what is now Algeria and Morocco to the South as it expanded in that direction as well.
The rare mtDNA haplogroup V is found all along the maritime path of this group of Mesolithic people's expansion (although later studies have shown mtDNA V in Eastern and Central Europe as well). For example, a new study documents a Kurgan burial of an individual from the Novosvobodnaya culture in a part of what is now Southern Russian in the Northern Caucasus mountains around 3,000 BCE with mtDNA haplogroup V7. The author of this new paper argues from this one ancient DNA sample that the mtDNA V7 points to a link with the contemporaneous Funnelbeaker culture (often abbreviated TRB from its German spelling) further North which was characterized by herding, fishing, marginal grain farming, and the use of imported copper but not Bronze, on the grounds that there are some indications of cultural linkage between the two cultures and on the grounds that mtDNA V is found in some remains from the Linear Pottery culture (often abbreviated LBK) who were the first farmers of the region from which the author argues that the TRB is derived. (The lack of references to ancient TRB DNA to back up this claim, and reliance on a very outdated 1999 paper from Brian Sykes for the largely disproven hypothesis that most European mtDNA haplogroups have been widespread in Europe since the Upper Paleolithic era as a foundation for his analysis, undermines confidence in his conclusion, however.) Also, who is to say that mtDNA V didn't introgress from pre-existing Mesolithic European hunter-gathers of whom the early Finns were a part, into farmers on the frontier of the Neolithic revolution, rather than the other way around?
The other leading mtDNA haplogrop in the Saami is U5b, which is common in all European hunter-gatherer populations. But, the U5b is predominantly U5b1b1 (284 out of 292 individuals with U5b with all 8 outliers located in Southern Sweden at the fringe of the area where Saami people are found), compared to about 20% of Continental Europeans with mtDNA U5b.
Disregarding the editorial white lines of distribution provided by the author (source here), I would say that the U5b1b1 distribution is quite a good fit for the coastal migration route.
On the Y-DNA side, one of the three most common Y-DNA haplogroups of the Finns, I1, is associated with the pre-Neolithic population of Europe (or more precisely, with sister Y-DNA haplogroup I2) much like mtDNA U5b and to a lesser extent mtDNA V (which is also found in ancient DNA in some early Neolithic populations in Europe, although possibly as a result of the first farmers of Europe taking wives from prior hunter-gatherer populations).
These people may have been the source population designed Western European Hunter-Gatherer based in ancient autosomal DNA, one of the three populations, together with "Early European Farmers" and "Ancestral Northern Eurasians" who were the main contributors to modern European population genetics in most of Europe (although as explained below, Finland had another Uralic population that contributed to its population genetics).
Mesolithic Archaeological Cultures In Finland
From 9000 BCE (or 7300 BCE if the reference is inaccurate) until about 2500 BCE, Finland was inhabited by the descendants of these people, who fed themselves mostly by fishing supplemented by hunting and gathering, without farming or herding.
Ulitmately, the Comb Ceramic culture, which was closely akin to the Pitted Ware people of mainland Europe nearby on the Baltic Sea, emerged from these people, around 5300 BCE, as they engaged in trade with Neolithic cultures to the South.
For example, flint from Scandinavia and the Valdai Hills, amber from Scandinavia and the Baltic region and slate from Scandinavia and Lake Onega found their way into Finnish archeological sites, while asbestos and soap stone from e.g. the area of Saimaa spread outside of Finland. Rock paintings—apparently related to shamanistic and totemistic belief systems—have been found, especially in Eastern Finland, e.g. Astuvansalmi.Farming and Herding Arrive In Finland
Around 2500 BCE (or perhaps as late as 2300 BCE), Finland's Comb Ceramic maritime culture merged with the linguistically Indo-European Corded Ware culture derived Battle Axe culture from the south (that made its first inroads into Southwest Finland ca. 3200 BCE) to give rise to the Kiukainen culture. The Battle Axe culture brought dairy farming and greatly disrupted the local culture, although less the ideal climate conditions impaired the desirability of the area for herding and farming, ultimately led to a resurgence in maritime fishing people's to the local culture, so that both cultures made significant contributions.
It hasn't been clear until this week how much of a contribution this archaeological culture made to the further Northern Saami people, but the sudden appearance of dairy farming as evidenced by residues on pottery suddenly appearing around 2500 BCE even above the Arctic Circle, puts to rest the possibility that dairying didn't reach the far northern reaches of Finland at that time. It is now clear that almost everyone in the region was affected as the Neolithic revolution finally reached Finland, even if some populations subsequently reverted to a different subsistence mode.
Indo-European Farmer Genetics
The Battle Axe culture is the likely source of Y-DNA haplogroup R1a in Finns and possibly also mtDNA H mostly arrive at this time (although the antiquity of mtDNA H in the region in ancient suggests that this haplogroup could have arrived in the Mesolithic, rather than a Neolithic era.
Notably, in Japan, whose Jomon culture was also maritime fishing based before the arrival of the Yaoyi rice farmers with horse riding warriors, there the indigeneous maritime culture also had a considerable population genetic contribution, rather than the predominant replacement of terrestrial hunter-gatherers seen elsewhere. More sedentary fishing cultures may have had more staying power vis-a-vis early farmers than terrestrial hunters and gatherers.
The Case For An Indo-European Language Shift
At this point in time, the population of Finland probably came to speak an Indo-European pre-Slavic Baltic language. (A Finnish linguist argues that this Corded Ware language was proto-Germanic, but in my view a Baltic language is more likely.)
The ancestral language of the Comb Ceramic and Pitted Ware peoples was probably lost at this time in what was probably one of its last outposts in Europe (after earlier episodes of Neolithic replacement or conquest in Continental Europe starting ca. 5500-4600 BCE), except for some place names and perhaps some twice removed substrate influences.
This first farmer Neolithic era probably persisted until the arrival of the that persisted until the Finish Bronze Age (ca. 1500 BCE-500 BCE).
The Finnish Bronze Age
Another Language Shift
Sometime after 2500 BCE, Finland received an influx of a Uralic language speaking population from Siberia, not closely related to either of its source populations.
This influx gave rise to a language shift during which the Finnish language (or at least the Finno-Saami language family) probably emerged. The Finnish Bronze Age exactly coincides with a statistical estimate of the time of origin of the Finno-Saami branch of the Uralic languages.
Realistically, the Uralic language probably arrived as part of the advent of the Finnish Bronze Age ca. 1500 BCE which arrived with Bronze using cultures from Northern and Eastern Russia according to Wikipedia with is in accord with this source regarding the earliest appearance of Bronze artifacts being located inland. But, an unsourced Internet resource claims a Western rather than Eastern source for the Finnish Bronze Age and the appearance of the Western practice of cremation around this time in Finland argues for a Western source in coastal areas. These differences of opinion regarding the origin of the Finnish Bronze Age had nationalist implications for Finland.
Like Razib, I disagree with the Wikipedia analysis that puts the arrival of the Uralic languages according to older scholarship, in Finland ca. 4000 BCE. The Wikipedia analysis acknowledges the possibility that this is inaccurate, but suggests an Iron Age arrival for Uralic, which I suspect is too late, although a differentiation of Finnish from neighboring Uralic languages may date to the Iron Age ca. 500 BCE.
The Genetic Impact of Bronze Age Uralic Migration Into Finland
Razib notes that they left an east Asian autosomal genetic contribution (about 5%-8% in Saami populations today), mtDNA (mtDNA haplogroups D5 and Z which make up a similar percentage of Saami mtDNA with the mtDNA Z1 subclade contribution dated to 2,000-3,000 years ago by mtDNA mutation rate dating, i.e. the Iron Age) and Y-DNA legacy (e.g. Y-DNA haplogroup N1b and N1c1), which is distinct from the "ancestral North Asian" autosomal genetic legacy in Europe (that may have arrived with first and/or subsequent waves of Indo-Europeans together with, for example, Y-DNA haplogroup R1a).
About the Uralic Language Family
The Uralic language family is shared by the people of Estonia, Latvia, the Karelian region of Russia, and the Saami people of Finland. A more distant branch of this language family is Hungarian, and another more distant branch of this language family is shared by many Siberian ethnic populations including the Mari who are arguably the last population to have continuously practiced pagan religions of Northern Asia into the present.
Some linguists such as Michael Fortescue writing in 1998, have argued that the Eskimo-Aleut languages, including Inuit, are a sister language family to the Uralic languages that together form a circumpolar mega-language family. Morris Swadesh in 1962, Holst in 2005, and others dating back to the 1746 CE, have made similar proposals.
From a historical timing perspective, however, the Saqqaq (Arctic Paleo-Eskimos) which was present 2000-2500 BCE (the best ancient DNA example of which had Y-DNA Q1a, mtDNA D2a1, and autosomal DNA similar to the modern Koryak people of the Northeast Asia coast) , or the Dorset (second wave Arctic Paleo-Eskimos) would be a better match, and perhaps left a substrate influence on later Eskimo-Aleut languages (although there are genetic indications that these earlier populations were almost totally replaced in the Americas) which arrived with the Thule around 500 CE. Inuits lack Y-DNA N1b and N1c found in modern Finns and contributed mostly mtDNA haplogroups A (which is absent in the Finns) to the existing indigenous American mtDNA pool, while the Dorset contributed mostly mtDNA D3 (found in modern Paleo-Siberian populations and which is a sister clade to Finnish and Asian mtDNA D5), according to the ancient DNA samples.
The Bronze Age Transition Was Demographically More Important Than The Iron Age Transition
The fact that the Finnish Bronze Age arrived from the Uralic heartland with a probable demic component, while the Finnish Iron Age appears to have include more cultural exchange than demic migration, and the likely powerful capacity of a metal age culture to overwhelm a pre-metal age culture militarily, argues for an arrival ca. 1500 BCE, rather than earlier or later. Certainly, this Siberian centered linguistic family would not have appeared at a time when the cultural influences in Finland were from Rome or Western Europe as it was from 0 CE onward.
One archaeological site from the period is this one and a number of Finnish Bronze Age papers from 2009 can be found here).
The Finnish Iron Age and the Middle Ages
The Finnish Iron Age began around 500 BCE (several hundred years later than in the Mediterranean) and around 0 CE, began to show the influence of trade with the Roman Empire that persisted until about 400 CE. The Migration Period during which there were mass folk migrations of "barbarian" Germanic tribes like the Goths and the Visigoths through Europe extended to Finland's Iron Age from ca. 400 CE to 575 CE and showed increasing Germanic influence in cultural artifacts.
The Migration period and the Merovingian period that followed also coincide historically with Slavic expansion into what is now Orthodox Christian Eastern Europe.
From 575 CE to 800 CE, "The Merovingian period in Finland gave birth to distinctive fine crafts culture of its own, visible in the original decorations of domestically produced weapons and jewelry. Finest luxury weapons were, however imported from Western Europe. The very first Christian burials are found from the latter part of this era as well. The Leväluhta burial findings suggest that the average height of a man was 158 cm [i.e. 5'2"] and that of a woman was 147 cm [i.e. 4'10"]."
Trade with the linguistically Germanic (Indo-European) Vikings (many from Sweden and some of whom started to colonize Finland) followed from 800 CE to 1025 CE during which hill forts started to be erected in Southern Finland in the earliest signs of urbanization.
The Christianization of Finland began in earnest around 1150 CE which was also around the time that Finland begins to appear in the written historic record. Swedish colonization efforts directed at Finland were stepped up in Northern Crusades in the early 1200s CE, bringing with them the other of Finland's two major languages and adding a significant Swedish population genetic component to the overall mix. According to Wikipedia the story then continued as follows:
In the early 13th century, Bishop Thomas became the first bishop of Finland. There were several secular powers who aimed to bring the Finns under their rule. These were Sweden, Denmark, the Republic of Novgorod in Northwestern Russia and probably the German crusading orders as well. Finns had their own chiefs, but most probably no central authority. Russian chronicles indicate there were conflict between Novgorod and the Finnic tribes from the 11th or 12th century to the early 13th century.Trade exchanges during the early Iron Age probably did not lead to language shift, and even the influx of Swedish and other Scandinavian colonists in starting in the Viking era around 1200 CE only led to a bilingual situation with coastal colony towns speaking Germanic Swedish languages with a Finnish substrate and Finnish and Saami remaining living languages elsewhere.
The name "Finland" originally signified only the southwestern province that has been known as "Finland Proper" since the 18th century. Österland (lit. Eastern Land) was the original name for the Swedish realm's eastern part, but already in the 15th century Finland began to be used synonymously with Österland. The concept of a Finnish "country" in the modern sense developed only slowly during the period of the 15th–18th centuries.
It was the Swedish regent, Birger Jarl, who established Swedish rule in Finland through the Second Swedish Crusade, most often dated to 1249, which was aimed at Tavastians who had stopped being Christian again. Novgorod gained control in Karelia, the region inhabited by speakers of Eastern Finnish dialects. Sweden however gained the control of Western Karelia with the Third Finnish Crusade in 1293. Western Karelians were from then on viewed as part of the western cultural sphere, while eastern Karelians turned culturally to Russia and Orthodoxy. While eastern Karelians remain linguistically and ethnically closely related to the Finns, they are considered a people of their own by most. Thus, the northern border between Catholic and Orthodox Christendom came to lie at the eastern border of what would become Finland with the Treaty of Nöteborg in 1323.
During the 13th century, Finland was integrated into medieval European civilization. The Dominican order arrived in Finland around 1249 and came to exercise huge influence there. In the early 14th century, the first documents of Finnish students at Sorbonne appear. In the south-western part of the country, an urban settlement evolved in Turku. Turku was one of the biggest towns in the Kingdom of Sweden, and its population included German merchants and craftsmen. Otherwise the degree of urbanization was very low in medieval Finland. Southern Finland and the long coastal zone of the Bothnian Gulf had a sparse farming settlement, organized as parishes and castellanies. In the other parts of the country a small population of Sami hunters, fishermen and small-scale farmers lived. These were exploited by the Finnish and Karelian tax collectors.
Finland In The Early Modern Era
Swedish domination would continue for centuries, and in the Reformation, the Swedish sided with the Protestant Lutherans against the Catholics and had their own round of witch hunting in the 1600s, including well as a short lived effort to establish a Swedish colony in America near the Delaware-Pennsylvania area from 1638-1655 CE, with at least half of the colonists coming from Finland.
Very hard times followed for the next quarter century resulting in the death of a third of the population in a four year long famine, followed by the death of half of the population in a twenty-one year long war. The population of Finland fell by about two-thirds in a single generation.
In 1696–1699, a famine caused by climate decimated Finland. A combination of an early frost, the freezing temperatures preventing grain from reaching Finnish ports, and a lackluster response from the Swedish government saw about one-third of the population die. Soon afterwards, another war determining Finland's fate began (the Great Northern War of 1700–21). The Great Northern War (1700–1721) was devastating, as Sweden and Russia fought for control of the Baltic. Harsh conditions—worsening poverty and repeated crop failures—among peasants undermined support for the war, leading to Sweden's defeat. Finland was a battleground as both armies ravaged the countryside, leading to famine, epidemics, social disruption and the loss of nearly half the population. By 1721 only 250,000 remained.Constitutional monarchy with a powerful parliament followed in Sweden, but "Finland by this time was [still] depopulated, with a population in 1749 of 427,000." Potato farming (which was a dietary staple of my ancestors) arrived after the 1750s.
In 1809, Finland was annexed to Russia with the assent of a popular assembly.
Mass migration to the United States in the late 19th century was also accompanied by hard times at home in Finland.
Finland secured independence in 1917, followed by a brief civil war in 1918, as a result of the Russian revolution.