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.
Language policy in Latvia
Since the beginning of the 1990s, some Polish language schools were created besides the existing schools with Latvian and Russian language of instruction. Certain schools (e.g., Riga Dubnov Jewish Secondary school, founded in 1989, and Riga Ukrainian Secondary School, founded in 1991, which had originally used Ukrainian as language of instruction, but switched to Latvian in 1993/1994) now include in their curriculum lessons in respective minority languages. The number of Russian schools is decreasing, partly due to natural demographic decline and partly due to emigration, as the following table demonstrates, with some schools with apparent viability closed. 
As at 2007, there was also increasing number of minority children attending Latvian-language schools.
According to Education law, as adopted in 1998, the language of instruction in public secondary schools (Forms 10-12) had to be only Latvian since 2004. This has mostly affected Russian schools, some existing in Latvia without interruption since at least 1789. After protests in 2003 and 2004, the law was amended allowing to teach up to 40% of curricula in minority languages (Transition Rules) and allowing orphans to continue their education not only in Latvian, but also in the language he or she began it (Section 56).