On 16 April 1879 in the old Bulgarian capital Tarnovo all 229 deputies in the Constituent Assembly signed the first Constitution of the Principality of Bulgaria which defines the administrative division of this country:
|“||The territory is divided into administrative okrazhia, okolia and obshtina.||”|
From 1885 to 1947 the okolia was secondary administrative territorial unit after the primary unit (okrazhie, okrag, oblast). In 1947 in the People's Republic of Bulgaria the oblasts are closed and as the primary administrative territorial unit remain 102 okolias of which 7 are urban (Sofia, Plovdiv, Stara Zagora, Burgas, Varna, Ruse and Pleven). In 1959 the 117 okolias are abolished and the People's Republic of Bulgaria was divided into 30 okrags.