See Archdiocese of the Goths and the Northlands for the 1994 establishment in Sweden.
The Metropolitanate of Gothia (also of Gothia and Caffa), also known as the Eparchy of Gothia or Metropolitanate of Doros, was a metropolitan diocese of the Patriarchate of Constantinople in the Middle Ages.
The 9th-century Metropolitanate of Doros was centered in the Crimea, but it seems to have had dioceses further afield, as far east as the Caspian coast, but they were probably short-lived, as the Khazars converted to Judaism. From the 13th century until the Ottoman conquest in 1475, the Metropolitanate of Gothia was within the Principality of Theodoro (known in Greek as Γοτθία, Gothia). In 1779, it was transferred to the Russian Orthodox Church and disestablished a few years later.
Early history
The Goths came into contact with Christianity from the late 3rd century, and were Christianized in the course of the 4th century. Theophilus, the first known bishop of the Goths, defended the Trinitarian and Orthodox Christological position against the Arians at the First Ecumenical Council in Nicea 325, and signed the Nicene Creed. The evidence suggests that Theophilus was the bishop of a territorial see in area of Crimea. The bishops of Crimean Gothia were Nicene (whereas most of the Goths were Arians) and were appointed by the patriarch of Constantinople.
The Crimean Goths themselves were a remnant of the migration-era Gothic population of Oium. The Byzantine Metropolitanate, however, was limited to a remnant of the Roman Crimea (the Bosporan Kingdom), consisting only of the southeastern coastal area of the peninsula. The Crimean Goths from about 370 were thus wedged between the Hunnic Empire (and later Khazaria) to the north and the Roman (Byzantine) territory to the southeast.
The "Archdiocese of the Goths" existed autonomously during the 5th to 9th centuries, but from the 5th century there seems to have been a close relation to the Patriarchate of Constantinople. John Chrysostomos consecrated Unila (d. 404) as bishop of the Archdiocese of the Goths. John Chrysostomos preached to the Goths with aid of interpreter in the Goths' church in Constantinople, which had priests, deacons and readers whom were Goths and read, preached and sang in the Gothic language. It was he who appointed the successor of Bishop Unila to the seat of ruling bishop over the Archdiocese of the Goths, and acted as the protector and benefactor of the Archdiocese at this period.
In its disputed 28th Canon, the Council of Chalcedon in 451 recognized an expansion of the boundaries of the Patriarchate of Constantinople and of its authority over bishops of dioceses "among the barbarians", which has been variously interpreted as referring either to areas outside the Byzantine Empire or to non-Greeks.
Byzantine metropolitanate
John of Gothia (John of Partenit) was a Metropolitan bishop of Doros. During the period of Byzantine Iconoclasm, John reputedly gathered Orthodox refugees from Constantinople in the Crimea. A bishop of Gothia attended the iconoclastic Council of Hieria in 754, but his flock soon expelled him and elected John in his place. John overthrew and expelled the Khazars from Gothia 787; the Khazars however managed to retake the city in less than a year, and John was imprisoned in Phoulloi. He later managed to escape, and sought refuge in Amastris in the Byzantine Empire, where he died in 791. His remains were brought home to a church on the Ayu-Dag mountain, where a memorial to him has been built. John's Vita was composed within a generation or so of his death, in the early 9th century.
The Gothic church was incorporated into the Patriarchate of Constantinople at some point between the late 8th and the late 9th century. It was the first diocese established outside the historical boundaries of the Roman Empire (just before the Metropolitanates of Alania and of Rus'). Its existence is documented in a list of Byzantine dioceses in a Paris manuscript, dated to the 14th century, published by Carl de Boor in 1891. Its continued existence is a matter of doubt, as there are practically no records on it, and it may have been little more than a missionary project with the aim of evangelizing the Khazars, or essentially a diocese in partibus infidelium. The archidiocese with its seat at Doros comprised seven dioceses (most of which correspond to unknown or uncertain locations).