It was especially implemented in northern Albania and in parts of Kosovo (Sanjak of Prizren and Sanjak of Scutari), where in the 19th century these regions constituted the frontier with the Principality of Serbia and Principality of Montenegro. These sanjaks had notable communities of Gheg Albanians (Muslims and Catholics), Serbs and Slavic Muslims. The Albanians adopted the system into their clan structure, and bajraks endured during the Kingdom of Serbia (1882–1918) and People's Socialist Republic of Albania (1944–1992).