Chaldia (Greek: Χαλδία, Khaldia) was a historical region located in the mountainous interior of the eastern Black Sea, northeast Anatolia (modern Turkey).

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.

[3] Initially, the name Chaldia was consigned to the highland region around Gümüşhane,[4] in northeast Anatolia, but in the middle Byzantine period, the name was extended to include the coastal areas, and thus the entire province around Trapezus (Trebizond, modern Trabzon).

Forming the easternmost area of the Pontic Alps, Chaldia was bounded to the north by the Black Sea, to the east by Lazica, the westernmost part of Caucasian Iberia, to the south by Erzincan, Erzurum and what the Romans and Byzantines called Armenia Minor, and to the west by the western half of Pontus.

The mountainous interior to the south, known as Mesochaldia ("Middle Chaldia"), was more sparsely inhabited and described by the 6th-century historian Procopius as "inaccessible", but rich in mineral deposits, especially lead, but also silver and gold.

The mines of the region gave the name Argyropolis ("silver town", modern Gümüşhane) to the principal settlement [citation needed].

Only during the reign of the Byzantine emperor Justinian I (r. 527–565) were the warlike tribes, the Sannoi or Tzannoi, subdued, Christianized, and brought under central rule.

[17] The Empire of Trebizond managed to survive through successive upheavals by a combination of its inaccessible location, a small but capable army, and a sound diplomacy based on marriage alliances, before finally falling to the Ottomans in 1461.