Curonian

…inhabitants, the Latvian tribe of Curonians (Kurs, Cori, Cours; Latvian: Kursi). The duchy of Courland, formed in 1561, included this area as well as Semigallia (Zemgale), a region located east of Courland proper.

…principalities on the peninsula of Courland (modern Kurzeme). To the east were the Semigallians, in present-day central Latvia and portions of northern Lithuania. Eastern Latvia was inhabited by the Selonians and Latgalians. At least four major principalities can be distinguished among the latter.