The ancestors of Lithuanians came to the Baltic area most likely around 2500 bc. The first reference to them by name was in ad 1009 in a medieval German manuscript, the Quedlinburg Chronicle. With the rise of the medieval lords in Germany and Russia, Lithuania was constantly subject to invasion and attempted conquest. In the 13th century, when the Teutonic Knights, a German militaristic religious order, were establishing their power, the Lithuanians resisted. The various Lithuanian tribes united to form a loose federation under pagan chieftain Mindaugas. Mindaugas was baptized as a Christian in 1251 and subsequently crowned king of Lithuania under the authority of Pope Innocent IV. In about 1260 the Lithuanians defeated the Knights’ attempt to capture Lithuanian territory. In 1263 Mindaugas was assassinated, probably by pagan Lithuanian princes, and Lithuania officially reverted to paganism.

Lithuanians are an Indo-European people belonging to the Baltic group. They were the only branch within the group that managed to create a state entity in premodern times. The Prussians, overrun by the Teutonic Order in the 13th century, became extinct by the 18th century. The Latvians to the north were conquered during the first three decades of the 13th century by the Order of the Brothers of the Sword (this order became a branch of the Teutonic Order in 1237). The Lithuanians, protected by a dense primeval forest and extensive marshland, successfully resisted German pressure. Samogitia (Lithuanian: Zemaitija), lying between Prussia and Livonia, two lands already in the hands of the German crusading knights, was a particular object of German expansion. The German threat induced the Lithuanian tribes to unite in the middle of the 13th century under Mindaugas. He and his family were baptized in 1251, and two years later he was accepted into the feudal hierarchy of Europe by being crowned king of Lithuania by authority of Pope Innocent IV. Mindaugas, who had reverted to paganism, and two of his sons were assassinated in 1263. The Lithuanians retained their naturalistic pagan religion until the late 14th century.

Despite the earlier nonaggression pact, Germany invaded the USSR in June 1941. Large-scale anti-Soviet uprisings then took place in Lithuania. Unable to contend with both the revolt and the German onslaught, Soviet forces withdrew from Lithuania. During the Nazi occupation, Lithuanian resources were systematically pillaged and more than 200,000 Lithuanians, including an estimated 165,000 Jews, were killed. The Nazis nearly exterminated the entire Jewish population, which had constituted Lithuania’s largest minority group before the war.