In circa 930, the province was raided and temporarily occupied by the Bulgarians. The Bulgarians returned under Tsar Samuel who moved the centre of Bulgarian power south and west to Ohrid, and in ca. 980 seized much of the region, down to the Ambracian Gulf. This is evidenced from the fact that the territories that were under Bulgarian rule formed part of the autocephalous Archbishopric of Ohrid after the Byzantine conquest of Bulgaria by Emperor Basil II in 1018: thus the sees of Chimara, Hadrianopolis, Bela, Buthrotum, Ioannina, Kozyle, and Rogoi passed under the jurisdiction of Ohrid, while the Metropolitan of Naupaktos retained only the sees of Vonditsa, Aetos, and Acheloos. Basil II also founded a few smaller themes, comprising little more than a fortress and its immediate surroundings, those of Koloneia and Dryinoupolis, in what is today the Greco-Albanian border region. In 1040, following the murder of a corrupt and oppressive taxation official – according to John Skylitzes, the locals were notorious for being ready to revolt for fiscal reasons – most of the theme joined the uprising of Petar Delyan.