Dievas was the chief deity in which extinct Baltic language?
Dievas Lithuanian Dievas, Latvian Dievs, Latgalian Dīvs, Prussian Deywis, Yotvingian Deivas was the supreme god in the Baltic mythology and one of the most important deities together with Perkūnas. Dievas is a direct successor of the Proto-Indo-European supreme god *Dyēus of the root "*deiwo-". Its Proto-Baltic form was *"Deivas".
Lithuania proper Lithuania proper (Latin: "Lithuania propria" , literally: "Genuine Lithuania"; Lithuanian: "Didžioji Lietuva" ; Yiddish: ליטע‎ , "Lite") refers to a region which existed within the Grand Duchy of Lithuania, and where the Lithuanian language was spoken. The primary meaning is identical to the Duchy of Lithuania, a land around which the Grand Duchy of Lithuania evolved. The territory can be traced by Catholic Christian parishes established in pagan Baltic lands of the Grand Duchy of Lithuania subsequent to the Christianization of Lithuania in 1387. They were quite distinguishable, since Ruthenian parts of the Duchy have been already baptised in an orthodox manner. The term in Latin was widely used during the Middle Ages and can be found in numerous historical maps until World War I.