1934: The NKVD was formed to combat opposition, and created a permanent form of terror
NKVD was crucial to the imposition of purges and helped to administer the Gulags
However, Stalin suspected the NKVD of conspiracy. By the start of WW2, the NKVD itself had been purged of around 20,000
In 1943, the NKVD was replaced with the NKGB, which was later replaced in 1946 with the MGB and the MVD. These merged in 1953 to form a larger version of the MVD