A country of north-central Europe on the Baltic Sea. The original inhabitants, the Letts, were conquered and Christianized in the 1200s by German knights, the Livonian Brothers of the Sword, who ruled the area until 1561, when it passed to Poland. Under Russian control from the 18th century, Latvia became independent after World War I but was annexed in 1940 by the USSR and known as the Latvian Soviet Socialist Republic until it declared its independence in 1990. Riga is the capital.