In the 6th century, probably at the end of the reign of Justinian I, the status of Roman Crimea changed. Taurica became the  Province of Chersonesos, which also included Bosporos and the southern coast of Crimea. This enlargement of Byzantine Taurica resulted in the elevation of the ranks of its governors. In the second half of the 6th century, the military and civil authorities in the region were entrusted to the military deputy, "doux Chersonos". Furthermore, the city of Chersonnesos was used by the Romans as a place of banishment: St. Clement of Rome was exiled there and first preached the Gospel. Another exile was Justinian II, who is said to have destroyed the city in revenge. Most of Roman Crimea fell under Khazar overlordship in the late 7th century. In the mid-8th century the rebellious Crimean Goths were put down by the Khazars and their city, Doros , was  occupied.  A Khazar tudun  was resident at Chersonesos already in 690, despite the fact that this town was nominally subject to the Byzantine Empire.  The Byzantine emperors controlled the southern shores of the Crimea peninsula until the 13th century. Control then passed to the Empire of Trebizond, one of the successor states to the Byzantine Empire after the sack of Constantinople in 1204. Another offshoot, the Principality of Theodoro, endured until 1475, when it was conquered by the Ottoman Empire. There are many series of Roman coins from the 1st century BCE to about 300, and also some from the Byzantine period.
Question: Who controlled the city of Chersonnesos?
Answer: Byzantine Empire