The Kazakh nation emerged in the fifteenth century from Turkic and Mongol peoples living in the area of modern Kazakhstan. Contact with Russia began in the sixteenth century. By the nineteenth century, vast areas of the steppes had been taken over by Russian and other settlers. After the Russian revolution in 1917, Kazakhstan declared itself independent but came under Bolshevik power in 1920. The Kazakh Autonomous Soviet Socialist Republic was declared in 1920, and became a separate republic within the Soviet Union in 1936. During Stalin's forced collectivization campaign in the 1930s, as much as one-third of the population perished. There were major boosts in industrialization during World War II (1939–45) and in grain and livestock production during the "Virgin Lands" campaign of the 1950s, but these also resulted in environmental degradation and human suffering. In December 1991, Kazakhstan and other Central Asian states insisted on being included in the newly formed Commonwealth of Independent States (CIS), made up of Armenia, Azerbaijan, Belarus, Georgia, Kazakhstan, Kyrgyzstan, Moldova, Russia, Tajikistan, Turkmenistan, Ukraine, and Uzbekistan. In joining the CIS, Kazakhstan hoped to maintain economic links with the Slavic republics and assuage its large Russian minority.