Under the Treaty of Paris 1856 the precipitates of Moldovia and Wallachia united to form Romania in 1862; when Austro Hungary was broken up in 1918 following the First World War, Romania expanded to include Bessarabia, Bucovina, and Transylvania. In 1940 certain territories were ceded to Bulgaria and the USSR. In 1944 Romania was occupied by Soviet forces. Following King Michael's abdication in 1947 the country came under the control of the Romanian Communist Party and declared itself a republic. Ties with the USSR loosened in the 1960s and closer links established with the West. Revolution in December 1989 led to the overthrow of the regime of the Communist dictator Nicolae Ceausescu and his regime. A new constitution which guarantees human rights and ensures a free market economy and democracy, has been adopted. The country incorporates some of Europe's most fertile land and thus farming is a major industry; there are also extensive forests, making the timber industry prominent. Romania also produces oil, natural gas, chemicals, copper, iron, and steel. Eastern Orthodox Christianity is the main religion; Romanian is the official language although French is also commonly spoken.