Finnish vatsa ~ Sanskrit vatsá and the formation of Indo-Iranian and Uralic languages

Finnish vatsa ‘stomach’ < PFU *vaćća < Proto-Indo-Aryan *vatsá- ‘calf’ < PIE *vet-(e)s-ó- ‘yearling’ contrasts with Finnish vasa- ‘calf’ < Proto-Iranian *vasa- ‘calf’. Indo-Aryan -ts- versus Iranian -s- reflects the divergent development of PIE *-tst- in the Iranian branch (> *-st-, with Greek and Balto-Slavic) and in the Indo-Aryan branch ( > *-tt-, probably due to Uralic substratum). The split of Indo-Iranian can be traced in the archaeological record to the differentiation of the Yamnaya culture in the North Pontic and Volga steppes respectively during the third millennium BCE, due to the use of separate sources of metal: the Iranian branch was dependent on the North Caucasus, while the Indo-Aryan branch was oriented towards the Urals. It is argued that the Abashevo culture of the Mid-Volga-Kama-Belaya basins and the Sejma-Turbino trade network (2200–1900 BCE) were bilingual in Proto-Indo-Aryan and PFU, and introduced the PFU as the basis of West Uralic (Volga-Finnic) into the Netted Ware Culture of the Upper Volga-Oka (1900–200 BCE)