Malagina (Greek: Μαλάγινα), in later times Melangeia (Μελάγγεια), was a Byzantine district in the valley of the Sangarius river in northern Bithynia, which served as a major encampment and fortified staging area (aplekton) for the Byzantine army. Malagina was the aplekton closest to the imperial capital of Constantinople, and as such of major importance during imperial expeditions to the East: it was here that the armies of the powerful themes of Anatolikon, Opsikion and Thrakesion joined the emperor. The region was also the site of the major imperial horse ranches (metata) in Asia Minor. It is first mentioned in historical sources in 798, when Empress Eirene assembled an army there. The site was attacked by the Arabs in 798, 860 and in ca. 875. In the 12th century, Emperor Manuel I Komnenos restored the fortifications of the district's main fortress at Metabole, and used it as a base for his campaigns against the Seljuk Sultanate of Iconium. Under the Angeloi, it became a separate province, headed by a governor titled dux and stratopedarches. At the same time, it is attested as being an archbishopric, before being raised to a metropolis under the Laskarids.