The theme of Chaldia (Greek θέμα Χαλδίας, theme Chaldias ) was a Byzantine theme on the Black Sea coast of Asia Minor ( modern Turkey ), which was established in the year 840. During the late Middle Ages, it was the heart of the Empire of Trebizond until his case 1461.
As the topics system was set up in the second half of the 7th century, the territory of the former Pontus Polemoniacus and part of Armenia I was known as Keltzene, part of the Armeniakon. Originally, it was as Turma (Department) of Chaldia organized later than Doukaton or archon. In the year 840, perhaps even 824, it was re- written as a separate topic. Arab geographers of the 9th and 10th centuries make different statements about this subject: Ibn Chordadhbeh talks about 6 fortresses in the topic, Qudama ibn Ja'far of about 4,000 soldiers as militia of the topic while Ibn al -Faqih reported the strategos of the theme 's commanding had 10,000 men had been available ( certainly exaggerated). The strategos of Chaldia received 20 pounds of gold as annual wages, half of which the state paid. The other half was provided by tax revenue as the Kommerkion tax that was levied on imported merchandise from the East. In the early 10th century, the district of Keltzene was deducted from the subject and added to the new topic Mesopotamia.
Up to the territorial expansion in the 10th century in the East Chaldia was the northeastern border of the Byzantine Empire. During the period of 1091/1095-1098 and 1126-1140, the area was virtually independent of Constantinople Opel. In the first of these periods Chaldia had been cut by the Seljuks from the remaining Byzantine territory, while had rebelled II Komnenos at the second time of Constantine Doux Gabras against Emperor John. After the dissolution of the Byzantine Empire during the Fourth Crusade in 1204 was the subject of part of the new Empire of Trebizond. This Empire, however, was practically reduced in the 14th century to the Chaldias area. The Empire succeeded because of its mountainous location, a small but effective army, as well as a thoughtful diplomacy to survive longer than the Byzantine Empire before 1461 and the Ottoman Empire fell. Even then still opposed some mountain fortresses the Ottomans. Only in 1479 the region was fully subjected when the fortress Golacha, the last Christian outpost in Asia Minor fell to the Turks. A large number of Pontic Greeks remained throughout the period of the Ottoman Empire on the Black Sea coast, until they were expelled in 1923.