A titular see in Armenia Prima. Colonia should be identified with Kara Hissar, chief town of a sanjak of the vilayet of Sivas. It has about 10,000 inhabitants, all Mussulmans, excepting 700 Greeks, and 2500 Armenians (1500 Gregorian, 700 Protestant, and 300 Catholic). It trades in agricultural products and alum from the neighbouring mines. Colonia retained its importance under the Seljukian Turks and even under the Ottomans, who captured it in 1473. In the present city there are the curious ruins of the citadel built by Justinian, and rebuilt and enlarged during the Middle Ages. Colonia was one of the centres of the Paulician heresy.
For the identification of Colonia see RAMSEY, Asia Minor, 57, 267; F. AND E. CUMONT, Studia Pontica (Brussels, 1906), 296-302. For the modern city see CUINET, La Turquie d' Asie, I, 779.
S. Pétridès.