- From the longer Wikipedia page 
The Southern Group of Forces (YUGV) was a Soviet Armed Forces formation formed twice following the Second World War, most notably around the time of the Hungarian Revolution of 1956.
On June 15, 1945, the 26th and 37th Soviet Armies (from 3rd Ukrainian Front) in Romania and Bulgaria, plus a division which had reached Yugoslavia, were grouped into the Southern Group of Forces.
The Group was re-created for a second time with its staff in Budapest seemingly during September 1955 (though former Soviet sources disagree; Feskov et al. say it was created on November 24, 1956). Lenskii says that it was re-created in 1955 to control the Soviet troops in Hungary following the disbandment of the former Central Group of Forces which had controlled troops in Austria and Hungary from 1945 to 1955, and the Soviet withdrawal from Austria. Under its command were the 2nd Guards 'Nikolayevsk-Budapest' Mechanised Division, the 17th Guards 'Yenakievskiy-Danube' Mechanised Division, two air divisions, and other troops. Lenskii says their function was 'to cover the boundary with neutral Austria and to guarantee communications in the case of the advancement of troops from the USSR'.
On October 24, 1956 the 33rd Guard Kherson Mechanized Division, previously stationed in Romania near the Romanian-Hungarian border, and two divisions from the Carpathian Military District, the 11th Guards 'Rovenskaya' Mechanized and 128th Guards Rifle Division, entered Hungary under the control of a Rifle Corps. The forces already in Hungary and those entering totalled 31,500 men. The 33rd Guards Mechanised Division took the lead role in suppressing the Hungarian Revolution in Budapest, and lost, according to Soviet sources, 14 tanks and assault guns as well as 9 armoured personnel carriers. Seven months afterward, on May 28, 1957, an agreement on the status of Soviet troops, comprising the Southern Group of Forces, was made between the USSR and Hungary.
The 11th Guards Mechanised and 128th Guards Rifle Divisions returned to the Carpathian Military District and were replaced by the 21st Guards 'Poltava' Tank Division and the 27th 'Cherkass' Motor Rifle Division, both under the command of the Carpathian Military District's 38th Army. 2nd Guards Mechanised Division was re-formed into the 19th Guards Tank Division, and the 17th Guards Mechanised Division was re-formed into the 17th Guard Motor Rifle Division and withdrawn to the USSR. The 33rd Guards Mechanised Division was then replaced by the 35th Guards 'Kharkov' Mechanised Division.