Sudak (Ukrainian and Russian: Судак; Crimean Tatar: Sudaq; Greek: Σουγδαία; sometimes spelled Sudac or Sudagh) is a city, multiple former Eastern Orthodox bishopric and double Latin Catholic titular see.

The city was in all likelihood founded by the Alans, as its name in Greek sources, Sougdaia is a cognate of the adjective sugda ("pure, holy") or derives from the word sugded/sogdad in the Ossetian language.

[2] Under Byzantine influence, the city was subject to Christianization, and became the seat of a bishopric under the Patriarch of Constantinople, attested for the first time in the Second Council of Nicaea in 787.

Archaeological evidence shows that the 6th-century constructions were abandoned in the 8th/9th century, while later Russian legends (probably apocryphal) claim that the city was captured by the Rus' chieftain, Bravlin, at around the same time.

[3] The 11th–14th centuries represent a period of prosperity for the city, as shown in archaeological evidence of renewed activity both in the harbour as well as the hinterland and the area of the citadel.

Burtas furs, beaver, squirrels ..."[4] By the mid-11th century, Sougdaia had returned to Byzantine control, probably following the defeat of the Khazar warlord Georgius Tzul in 1016.

Contemporary sources place its population at the time to 8,300, including Greeks, Alans, Mongols, Armenians, Latins, and Jews.

[2] At about the same time, the Tatars converted to Islam, which led to a deterioration of their relations with the Greek-speaking and Christian inhabitants of the city, many of whom were forced to leave it.

The Genoese refortified the city, constructing the citadel that is still visible today, and induced a large part of the deported Greeks to return.

Although Sudak was the strategical center of a qadılıq, the smallest administrative unit in the Ottoman Empire, the town lost much of its military and commercial importance, until the Crimean Khanate took over.

Under Genoese rule, a Latin Catholic diocese of Soldaia was established in 1390, which has had the following residential bishops : It was suppressed circa 1500 after the Ottoman conquest of the Crimea in 1475.

In a addition to the ethnic Russian majority, the city is also inhabited by big Ukrainian and Crimean Tatar minorities, which combined make up 35% of the population.