Latgalian language
Latgalian is spoken in Latgale, the eastern part of Latvia. It is debated whether it is a separate language or a distinct dialect of Latvian. Nevertheless, its standardized form is recognized and protected as a "historical variety of the Latvian language" "(vēsturisks latviešu valodas paveids)" by Latvian law. The 2011 Latvian census established that 8.8% of Latvia's inhabitants, or 164,500 people, speak Latgalian daily. 97,600 of them live in Latgale, 29,400 in Riga and 14,400 in the Riga region.
Latgalians
They likely spoke the Latvian language, which probably became the "lingua franca" in present-day Latvia during the Northern Crusades due to their alliance with the crusaders. Latgalians later assimilated the neighbouring tribes, forming the core of modern Latvians.