Ukraine is a former Soviet republic situated in south east Europe. In the mid thirteenth century it was invaded by Mongols. Then it was controlled for some 300 years by the Poles until Russia intervened on the understanding that it would gain sovereignty over the region. From the mid seventeenth century onwards Ukraine remained under Russian control. Then in 1918 it declared independence. However, in 1922 Ukraine again came under Soviet domination and it became a republic within the USSR. The republic suffered greatly during the Second World War with millions of its people dying. After great industrialisation in the post war period Ukraine declared its independence in 1991. In the south of the country there are vast coal deposits; and much iron and steel are also produced there. Agriculture is also important and on the Black Sea coast a lot of shipbuilding takes place. Russian and Autocephalous Orthodoxy are the chief religions and Ukrainian is the official language; however, Russian is also widely spoken.