Historically known as the "Arbër" or "Arbën" by the 11th century and onwards, they traditionally inhabited the mountainous area to the west of Lake Ochrida and the upper valley of the River Shkumbin. Though it was in 1190 when they established their first independent entity, the Principality of Arbër (Arbanon), with its seat based in Krujë. Immediately after the decline of the Progon dynasty in 1216, the principality came under Gregorios Kamonas and next his son-in-law Golem. Finally, the Principality was dissolved in ca. 1255 by the Empire of Nicea followed by an unsuccessful rebellion between 1257 and 1259 supported by the Despotate of Epirus. In the meantime Manfred, King of Sicily profited from the situation and launched an invasion into Albania. His forces, led by Philippe Chinard, captured Durrës, Berat, Vlorë, Spinarizza, their surroundings and the southern coastline of Albania from Vlorë to Butrint. In 1266 after defeating Manfred's forces and killing him, the Treaty of Viterbo of 1267 was signed, with Charles I, King of Sicily acquiring rights on Manfred's dominions in Albania. Local noblemen such as Andrea Vrana refused to surrender Manfred's former domains, and in 1271 negotiations were initiated.