Following several political unions with the Grand Duchy of Lithuania (Kreva Union 1385, Horodło Union 1413 and Lublin Union 1569) the Ruthenian and Lithuanian population in Poland was polonised. The largest region to be affected was the historic area of the Grand Duchy of Lithuania. Its inhabitants belonged to different ethnic and religious groups the most important being the Ruthenians (today Belarusians and Ukrainians) who were Byzantine Catholics. The Lithuanian- and Latvian-speaking inhabitants lived in the northern regions. Since the Polish influence was traditionally quite strong and Poland ruled Lithuania, the Poles were usually the landowners in those regions even though they only constituted the majority in Vilnius and Grodno. In total, there were 15% of Polish-speakers in the Grand Duchy of Lithuania and about as many Jews. With the divisions (1772-1795) the region was annexed by the Russian Empire.
According to the 2002 census 5,864 persons declared Lithuanian nationality. Estimates from different sources indicate a total of approx. 30,000 Lithuanians (Association for Civic Media 2003; Handbook of Contact Linguistics 1996). Most Lithuanians (84%) live in the Podlasie region in the administrative districts of Puńsk (Lithuanian: Punskas), Sejny (Lithuanian: Seinai) (38%) and to a lower extent in the district of Szypliszki (Lithuanian: Šipliskia). Many settled in the city of Suwalki. Other Polish Lithuanians dispersed during migration or immigration all over Poland, especially to the northern and south-western part of the country (Gdynia, Olsztn, Szezin and Wrozław). Many Lithuanians lived in the capital, Warsaw.