During the ll-14th centuries, no less than four Kipcak Turkic speaking groups settled in Eastern Europe: (a) the Tatars and Karaites settled in Byelorussian- and Ukrainian-speaking territories of the Grand Duchy of Lithuania in the 14th century; (b) Kipcak-speaking members of the Armenian Church settled in Galicia and Podolia beginning with the 11th century; (c) the Cumans settled in Hungary in the 11th century. Of these four groups, only the Karaites, descended from a Jewish sect founded in the 8th century in Iraq which rejects the authority of the oral law, have preserved their speech up to the present — though assimilation to Russian and other Soviet languages is now proceeding apace. The Tatars and Armenians apparently assimilated by the 16th century to Byelorussian and Ukrainian, while the Cumans became absorbed into the Hungarian speech community by the 18th century. The Byelorussian Tatars have long been the object of scholarly investigation. While their language disappeared without any significant written documentation, the Byelorussian Tatars are important to Byelorussian linguistics because they wrote Byelorussian in an Arabic-derived script from the 17th century up to the early 20th century, which allows us to reconstruct many features of the spoken language not systematically reflected in the traditional Cyrillic and Latin orthographies.