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.
Latgalians (modern)
During the first independence of Latvia (1918–1940), Latgale was the only region of Latvia with strong regional political parties. Although Latvian governments mainly promoted a united Latvian culture, fostering assimilation of Latgalians, especially after the coup by Kārlis Ulmanis in 1934, the Latgalian language was also used. Books were published in Latgalian, it was taught in some schools, and people could choose to use Latgalian when communicating with the government. They were classified as a Narodnosti in the First All Union Census of the Soviet Union in 1926. In the Nazi German "Generalplan Ost", as far as can be told from the surviving documentation, the Latgalians were scheduled for deportation, while only half of the Latvian population was to be treated so. The reasons for this difference are unclear, but possibly based on racist linguistic arguments, considering that the Nazis planned to physically remove 85% of the Lithuanians (whose language – and by erroneous inference ethnicity – has similarities to Latgalian).