the region, was engaged in repeated attacks against the Yugoslav police and army. During World War II Bulgaria retook the Western Outlands, as well as Pirot and Vranje. After the Second World War, these regions were returned to Yugoslavia. After Serbia's independence, these areas remained within Serbia. Demographics According to the 2011 census, there were 18,543 Bulgarians in Serbia. They are primarily located in two municipalities near Serbia's border with Bulgaria: in Bosilegrad there are 5,839 Bulgarians i.e. 71.9% of population while in Dimitrovgrad (Tsaribrod) there are 5,413 Bulgarians or 53.5% of population. The dominant religion among ethnic Bulgarians in Serbia is Orthodoxy. Islam never arrived in areas like Bosilegrad because of the mountainous terrain and most inhabitants dwelled in high mountain villages where they were hard to reach. They use both Serbian and Bulgarian churches due to the low number of Bulgarian clergymen present in the region. There is a church in every village around Bosilegrad, and the oldest ones date to the 11th century. Notable people Helena of Bulgaria, regent of Serbia 1355–1356 Gregory Tsamblak (c.1365–1420), medieval writer and cleric Vene Bogoslavov (1932-2015),mathematician References See also Bulgaria-Serbia relations Serbs in Bulgaria Western Outlands Bulgarians in North Macedonia Bulgarians Macedonian Bulgarians Shopi Serbia Ethnic groups in Serbia Serbia