The bajrak (pronounced /beɪrɑːk/ or /baɪrɑːk/, meaning "banner" or "flag") was an Ottoman territorial unit, consisting of villages in mountainous frontier regions of the Balkans, from which military recruitment was based. It was introduced in the late 17th century and continued its use until the end of Ottoman rule in Rumelia. The bajrak included one or more clans. 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).