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.
Russian language in Latvia
In 1989 Russian was the native language to 42% inhabitants, including 8% of population who were non-Russians, while 39% inhabitants spoke it fluently as a second language. From 1989 to 1990 an average of 47.5% pupils had enrolled in schools with Russian as the language of tuition, and the number was even higher (69.3%) in urban centers, suggesting that not only an overwhelming majority of non-Latvians, but also some Latvians had enrolled in Russian-language schools.