Kazakhstan is the world's ninth-largest country and the largest landlocked nation, located in Central Asia and Eastern Europe with a diverse landscape ranging from steppes to mountains. The country declared independence from the Soviet Union in 1991 and is now a republic with an authoritarian presidential system. Kazakhstan's economy is rich in natural resources, particularly oil and gas, and it is the largest economy in Central Asia. The official language is Kazakh, but Russian is also used for official purposes. Islam is the predominant religion, with a substantial Christian minority.