THE PEOPLES OF the southeastern shore of the Baltic Sea were among the last in Europe to accept baptism and abandon their ancestral religions. Indeed, in the twelfth century the persistence of ancestral religion in the Baltic region when the rest of northern Europe had been brought within Catholic or Orthodox Christendom inspired the Northern Crusades, a series of campaigns against the unconverted Slavs and Balts which eventually resulted in the establishment of the crusader states of Prussia and Livonia. While the Baltic peoples under the rule of crusading orders were forcibly (albeit often unsuccessfully) converted to Christianity, the Lithuanians and Samogitians not only remained ostentatiously pagan, but also expanded their rule over Orthodox principalities in today's Belarus and Ukraine until the Grand Duchy of Lithuania grew into one of the largest polities in Europe. Finally, between 1387 and 1417 Lithuania was formally (yet superficially) converted to Catholic Christianity. In the fifteenth and sixteenth centuries, the apparent continued existence of paganism in the Baltic fascinated a new generation of humanist historians and ethnographers in Poland, German Prussia, and elsewhere, who applied novel methods of historiography and ethnography to some of Europe's last pagan societies.

The Latin writings of humanist writers about Baltic religion constitute one of the most detailed collections of records of a non-literate ancestral religion in northern Europe. While there is no shortage of evidence from many European countries of “pagan” beliefs and practices deemed unacceptable by the church, the evidence for Baltic paganism stands apart because it was recorded by historians and ethnographers whose curiosity about paganism often went beyond the desire to condemn it. While attempts to suppress paganism were well underway in fifteenth-century Lithuania, there was also a new climate of secular scholarly curiosity in and about the Baltic region. The arrival of humanist learning in Poland and Prussia, along with the newly Christianized Lithuanian nobility's desire for a distinguished pedigree, produced intense curiosity about the origin of the Baltic peoples and their religion. As Lithuania took its place not only as one of the nations of Christendom, but also as a major Catholic power, Lithuania's history became a matter of European importance.

The transition from medieval antipagan polemic to humanist proto-ethnography in early modern writing on the Baltic peoples anticipated the far better-known development of sympathetic scholarly attitudes to the indigenous peoples of the New World.