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.
Ludza Estonians
By the 19th century the church had become Latvianised and Russian had become the official language and lingua franca. According to Oskar Kallas, who made a studying trip to area in 1893, there were 4,387 Ludza Estonians of whom some 800 could speak Estonian. In the 1970s and 80s, there were some 20 people left in the area still using the language, but it is now most likely to have perished. The dialect spoken by Ludza Estonians, was closely related to eastern Võro-dialects. It contained about 180 loanwords from Latvian language and some from Russian. Ludza Estonians reportedly had some difficulty understanding standard Estonian.