Ph2tḗr (lit. "sky father"; > Vedic Sanskrit Dyáuṣ Pitṛ́, Ancient Greek Ζεύς (πατήρ) / Zeus (dyeus)), vocative *dyeu ph2ter (> Latin Iūpiter, Illyrian Deipaturos) oral heroic poetry or song lyrics that used stock phrases such as imperishable fame (*ḱléwos ń̥dʰgʷʰitom) and the wheel of the sun (*sh₂uens kʷekʷlos). a patrilineal kinship-system based on relationships between men A 2016 phylogenetic analysis of Indo-European folktales found that one tale, The Smith and the Devil, could be confidently reconstructed to the Proto-Indo-European period. This story, found in contemporary Indo-European folktales from Scandinavia to India, describes a blacksmith who offers his soul to a malevolent being (commonly a devil in modern versions of the tale) in exchange for the ability to weld any kind of materials together. The blacksmith then uses his new ability to stick the devil to an immovable object (often a tree), thus avoiding his end of the bargain. According to the authors, the reconstruction of this folktale to PIE implies that the Proto-Indo-Europeans had metallurgy, which in turn "suggests a plausible context for the cultural evolution of a tale about a cunning smith who attains a superhuman level of mastery over his craft." History of research Researchers have made many attempts to identify particular prehistoric cultures with the Proto-Indo-European-speaking peoples, but all such theories remain speculative. The scholars of the 19th century who first tackled the question of the Indo-Europeans' original homeland (also called Urheimat, from German), had essentially only linguistic evidence. They attempted a rough localization by reconstructing the names of plants and animals (importantly the beech and the salmon) as well as the culture and technology (a Bronze Age culture centered on animal husbandry and having domesticated the horse). The scholarly opinions became basically divided between a European hypothesis, positing migration from Europe to Asia, and an Asian hypothesis, holding that the migration took place in the opposite direction. In the early 20th century, the question became associated with the expansion of a supposed "Aryan race", a now-discredited theory promoted during the expansion of European empires and the rise of "scientific racism". The question remains contentious within some flavours of ethnic nationalism (see also Indigenous Aryans). A series of major advances occurred in the 1970s due to the convergence of several factors. First, the radiocarbon dating method (invented in 1949) had become sufficiently inexpensive to be applied on a mass scale. Through dendrochronology (tree-ring dating), pre-historians could calibrate