The period 1937–45 saw numerous large scale deportations of various ethnic groups within the Soviet Union. These peripheral groups were seen as threats to the wartime stability of the Soviet Union and, as a result, were mostly sent to work in Siberian gulags or to populate forced labour camps in the southern Soviet Republics of Central Asia. The first large-scale deportation was of Korean migrants around Vladivostok in 1937. When Japan established rule over Korea, Koreans in Russia were perceived as a threat, so around 170,000 were relocated to Kazakhstan and Uzbekistan. Similarly, some 430,000 people of German descent in the Volga area were deported because of their supposed collaboration with Nazi Germany. Many ethnic groups in the Caucasus including Chechens, the Ingush, Crimean Tartars and Kalmyk were also forcibly deported under suspicion of assisting the Nazi German invasion, with many hundreds of thousands dying en route to, or in, the gulags.