After the capture of Constantinople by the Crusaders in 1204 the system of themes totally broke down. When the Byzantine Empire was reconstructed in 1261 Macedonia was organised in accordance with the administrative system of 'katepanikia'.
During the 14th century internal weaknesses of the centralised state led to the creation of principalities. These were regions granted to members of the imperial family and given economic and administrative independence.
Serbian and Turkish incursions into imperial territory in the course of the century alienated increasingly larger parts of Byzantium. Byzantine lands incorporated into the Ottoman Empire were, of course, absorbed into the administrative system of the Ottomans.