The history of the institution before the eighteenth century is obscure. The current scholarly consensus, based on comparative anthropological and linguistic evidence, is that Finnic-speaking cultures once shared in a wider central and northern Eurasian tradition of shamanism, most distinctively characterised by ritual specialists being believed to leave their bodies in spirit form. Such people were, in the Proto-Uralic language, probably denoted with the word *nojta (cf. Finnish noita 'witch' and Sámi noaidi). However, while tietäjä traditions clearly have important characteristics in common with shamanism, tietäjät were not believed to leave their bodies; their supernatural power arose rather from their command of memorised incantations and rituals. It is thought that these aspects of the tradition, and so the institution of the tietäjä as we know it, arose from contact with Germanic-speaking cultures, which exerted huge linguistic influence on Proto-Finnic language, and on other aspects of Finnic culture, in the first millennia BCE and CE. This is not to say that the tietäjä-institution was identical to its Germanic models, nor that it did not then change over time. Further influences, for example, came from later contact with Christianity.Frog, 'Shamans, Christians, and Things in Between: From Finnic-Germanic Contacts to the Conversion of Karelia', in Conversions: Looking for Ideological Change in the Early Middle Ages, ed. by Leszek Słupecki and Rudolf Simek, Studia Mediaevalia Septentrionalia, 23 (Vienna: Fassbaender, 2013), pp. 53–97, https://www.academia.edu/4049431 (esp. 61-67).
