They were among the last of the European peoples to be converted to Christianity, and in the 14th century they became Roman Catholics. The 14th-century union between Lithuania and Poland also influenced the culture, especially in Vilnius, which became a predominantly Polish city with a large Jewish population in the 17th century. Most of the Jewish population was murdered during the German occupation during World War II, and after the war most of Lithuania's Poles emigrated. After the annexation of Lithuania by the Soviet Union, many Russians moved to the republic. Before 1940 Lithuania's major economic activity was agriculture.
Livestock breeding is the single most important branch of agriculture.
Industrial production increased in spite of the lack of energy and other raw materials, which must be imported. A large hydroelectric plant is located on the Niemen River near Kaunas, and there are some thermal power stations, fired by peat or natural gas brought by pipeline from Ukraine. Lithuanian industry produces machine tools, refrigerators, washing machines, radio and television sets, and similar products that require skilled labor. Other industries include chemicals, textiles, and woodworking. There is a relatively dense railroad network.