Latgalian language
Originally Latgalians were a tribe living in modern Vidzeme and Latgale. It is thought that they spoke the Latvian language, which later spread through the rest of modern Latvia, absorbing features of the Old Curonian, Semigallian, Selonian and Livonian languages. The Latgale area became politically separated during the Polish–Swedish wars, remaining part of the Polish–Lithuanian Commonwealth as the Inflanty Voivodeship, while the rest of Latvians lived in lands dominated by Baltic German nobility. Both centuries of separate development and the influence of different prestige languages likely contributed to the development of modern Latgalian as distinct from the language spoken in Vidzeme and other parts of Latvia.
Demographic history of the Vilnius region
The city of Vilnius, now the capital of Lithuania, and its surrounding region have at various times come under Polish-Lithuanian, Russian, Polish, German, and Soviet rule. The population has been categorised by linguistic and sometimes also religious indicators. At the end of the 19th century the main languages spoken were Polish, Lithuanian, Belarusian and Russian. Both Catholic and Orthodox Christianity were represented, while a large proportion of those within the city were Jews. The "Lithuanian" element was seen as declining, while the "Slavic" element was increasing.