or grain-producing region for the Soviet Union. The Virgin Lands policy brought mixed results. However, along with later modernizations under Soviet leader Leonid Brezhnev, it accelerated the development of the agricultural sector, which remains the source of livelihood for a large percentage of Kazakhstan's population. By 1959, Kazakhs made up 30% of the population. Ethnic Russians accounted for 43%.
Growing tensions within Soviet society led to a demand for political and economic reforms, which came to a head in the 1980s. A factor that contributed to this immensely was Lavrentii Beria's decision to test a nuclear bomb on the territory of Kazakh SSR in Semey in 1949. This had a catastrophic ecological and biological effect that was felt generations later, and Kazakh anger toward the Soviet system escalated.
In December 1986, mass demonstrations by young ethnic Kazakhs, later called Jeltoqsan riot, took place in Almaty to protest the replacement of the First Secretary of the Communist Party of the Kazakh SSR Dinmukhamed Konayev with Gennady Kolbin from the Russian SFSR. Governmental troops suppressed the unrest, several people were killed and many demonstrators were jailed. In the waning days of Soviet rule, discontent continued to grow and find expression under Soviet leader Mikhail Gorbachev's policy of glasnost.
Independence
Caught up in the groundswell of Soviet republics seeking greater autonomy, Kazakhstan declared its sovereignty as a republic within the Union of Soviet Socialist Republics in October 1990. Following the August 1991 aborted coup attempt in Moscow and the subsequent dissolution of the Soviet Union, Kazakhstan declared independence on December 16, 1991. It was the last of the Soviet republics to declare independence.
The years following independence have been marked by significant reforms to the Soviet-style economy and political monopoly on power. Under Nursultan
