Soviet Army forces on USSR territory were apportioned among military districts. There were 32 of them in 1945. Sixteen districts remained from the mid-1970s to the end of the USSR (see table at right). Yet, the greatest Soviet Army concentration was in the Group of Soviet Forces in Germany, which suppressed the anti-Soviet Uprising of 1953 in East Germany. East European Groups of Forces were the Northern Group of Forces in Poland, and the Southern Group of Forces in Hungary, which put down the Hungarian Revolution of 1956. In 1958, Soviet troops were withdrawn from Romania. The Central Group of Forces in Czechoslovakia was established after Warsaw Pact intervention against the Prague Spring of 1968. In 1969, at the east end of the Soviet Union, the Sino-Soviet border conflict (1969), prompted establishment of a 16th military district, the Central Asian Military District, at Alma-Ata, Kazakhstan. In 1979, the Soviet Union entered Afghanistan, to support its Communist government, provoking a 10-year Afghan mujahideen guerrilla resistance