The Indo-Europeans who settled Europe, Western Asia and the Indian subcontinent conceived their societies to be ordered (not divided) in a tripartite fashion, the three parts being castes. Castes came to be further divided, perhaps as a result of greater specialisation.
The "classic" formulation of the caste system as largely described by Georges Dumézil was that of a priestly or religiously occupied caste, a warrior caste, and a worker caste. Dumézil divided the Proto-Indo-Europeans into three categories: sovereignty, military, and productivity (see Trifunctional hypothesis). He further subdivided sovereignty into two distinct and complementary sub-parts. One part was formal, juridical, and priestly, but rooted in this world. The other was powerful, unpredictable, and also priestly, but rooted in the "other", the supernatural and spiritual world. The second main division was connected with the use of force, the military, and war. Finally, there was a third group, ruled by the other two, whose role was productivity: herding, farming, and crafts.
This system of caste roles can be seen in the castes which flourished on the Indian subcontinent and amongst the Italic peoples.
Examples of the Indo-European castes:
Anglo-Saxon – Gebedmen (prayer-men), Fyrdmen (army-men), Weorcmen (workmen) (according to Alfred the Great)Slavic – Volkhvs, Voin, Krestyanin/Smerd
Kings were born out of the warrior or noble class.
 Mallory, J.P. In search of the Indo-Europeans Thames & Hudson (1991) p. 131.The entry on the Trifunctional Hypothesis further explains that:
The trifunctional hypothesis of prehistoric Proto-Indo-European society postulates a tripartite ideology ("idéologie tripartite") reflected in the existence of three classes or castes—priests, warriors, and commoners (farmers or tradesmen)—corresponding to the three functions of the sacral, the martial and the economic, respectively. The trifunctional thesis is primarily associated with the French mythographer Georges Dumézil who proposed it in 1929 in the book Flamen-Brahman, and later in Mitra-Varuna.Three-way division
According to Dumézil (1898-1986), Proto-Indo-European society comprised three main groups corresponding to three distinct functions:
* Sovereignty, which fell into two distinct and complementary sub-parts:* one formal, juridical and priestly but worldly;* the other powerful, unpredictable, and also priestly but rooted in the supernatural world.
In the Proto-Indo-European mythology each social group had its own god or family of gods to represent it and the function of the god or gods matched the function of the group. Many such divisions occur in the history of Indo-European societies:
* Southern Russia: Bernard Sergent associates the Indo-European language family with certain archaeological cultures in Southern Russia and reconstructs an Indo-European religion based upon the tripartite functions.
* Early Germanic society: The supposed division between the king, nobility and regular freemen in early Germanic society.
* Norse mythology: Odin (sovereignty), Týr (law and justice), the Vanir (fertility).[note 1] Odin has been interpreted as a death-god and connected to cremations, and has also been associated with ecstatic practices.
* Classic Greece: The three divisions of the ideal society as described by Socrates in Plato's The Republic. Bernard Sergent examined the trifunctional hypothesis in Greek epic, lyric and dramatic poetry.
* India: The three Hindu castes, the Brahmans or priests; the Kshatriya, the warriors and military; and the Vaishya, the agriculturalists, cattle rearers and traders. The Shudra, a fourth Indian caste, is an "outer" or serf caste serving the other three. A 2001 study found that the genetic affinity of Indians to Europeans is proportionate to caste rank, the upper castes being most similar to Europeans whereas lower castes are more like Asians. The researchers believe that the Indo-European speakers entered India from the Northwest, mixing with or displacing proto-Dravidian speakers, and may have established a caste system with themselves primarily in higher castes.
ReceptionThe hypothesis was embraced outside the field of Indo-European studies by some mythographers, anthropologists, and historians such as Mircea Eliade, Claude Lévi-Strauss, Marshall Sahlins, Rodney Needham, Jean-Pierre Vernant and Georges Duby. Supporters of the hypothesis include scholars such as Émile Benveniste, Bernard Sergent and Iaroslav Lebedynsky, who concludes that "the basic idea seems proven in a convincing way".
On the other hand, Allen concludes that the tripartite division may be an artefact, a selection effect rather than an organizing principle used in the societies themselves. Benjamin W. Fortson reports a sense that Dumézil blurred the lines between the three functions and the examples that he gave often had contradictory characteristics, causing detractors to reject his categories as non-existent. John Brough surmises that societal divisions are common outside of Indo-European societies as well, and consequently the hypothesis has only limited utility in illuminating prehistoric Indo-European society. Cristiano Grottanelli states that while Dumézilian trifunctionalism may be seen in modern and medieval contexts, its projection onto earlier cultures is mistaken. Belier is strongly critical.
The hypothesis has been criticised by historians Carlo Ginzburg, Arnaldo Momigliano and Bruce Lincoln as being based on Dumézil's sympathies with the political right. Guy G. Stroumsa sees these criticisms as unfounded.To the extent that this is an accurate characterization of Indo-European society is sheds a powerful light on what it would have been like to live at the time, although some of the applications given to the concept do seem muddy.