Chaldia (Greek: Χαλδία, Khaldia) was a historical region located in the mountainous interior of the eastern Black Sea, northeast Anatolia (modern Turkey) in Western Asia. Its name was derived from a people called the Chaldoi (or Chalybes) that inhabited the region in antiquity. Chaldia was used throughout the Byzantine period and was established as a formal theme, known as the Theme of Chaldia (Greek: θέμα Χαλδίας), by 840. During the Late Middle Ages, it formed the core of the Empire of Trebizond until its fall to the Ottoman Empire in 1461.
Anthony Bryer traces the origin of its name not to Chaldea, as Constantine VII had done, but to the Urartian language, for whose speakers Ḫaldi was the Sun God. Bryer notes at the time of his writing that a number of villages in the Of district were still known as "Halt". Other scholars, however, reject the Urartian connection. Χάλυψ, the tribe's name in Greek, means "tempered iron, steel", a term that passed into Latin as chalybs, "steel". Sayce derived the Greek name Chalybe from Hittite Khaly-wa, "land of Halys". More than an identifiable people or tribe, "Chalybes" was a generic Greek term for "peoples of the Black Sea coast who trade in iron".
