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.
Livonian language
Livonian has for centuries been thoroughly influenced by Latvian in terms of grammar, phonology and word derivation etc. The dative case in Livonian, for example, is very unusual in a Finnic language. There are about 2,000 Latvian and 200 German loanwords in Livonian and most of the German words were adopted through Latvian. Latvian, however, was influenced by Livonian as well. Its regular syllable stress based on Livonian is very unusual in a Baltic language. In both languages the letter "h" is silent, unlike other Finnic and Baltic languages. Especially as of the end of the nineteenth century there was a great deal of contact with Estonians, namely between (Kurzeme) Livonian fishers or mariners and the Estonians from Saaremaa or other islands. Many inhabitants of the islands of Western Estonia worked in the summer in Kurzeme Livonian villages. As a result, a knowledge of Estonian spread among those Livonians and words of Estonian origin also came into Livonian. There are about 800 Estonian loanwords in Livonian, most of which were borrowed from the Saaremaa dialect.1st Article of the Universal Declaration of Human Rights