A number of congregations of Russian Mennonites, Jehovah's Witnesses, and other Christian groups existed in the Soviet Union. Nearly 9,000 Jehovah's Witnesses were deported to Siberia in 1951; the numbers of those who were not deported is unknown. The number of Jehovah's Witnesses increased greatly over this period, with a KGB estimate of around 20,000 in 1968. Russian Mennonites began to emigrate from the Soviet Union in the face of increasing violence and persecution, state restrictions on freedom of religion, and biased allotments of communal farmland. They emigrated to Germany, Britain, the United States, parts of South America, and other regions.