Complete agreement has not yet been reached among students as to the part played by Egypt in the history of Early Christian and Early Byzantine art. There are two problems around which discussion has chiefly centred. The first concerns Alexandria. Some authorities believe that this town remained a stronghold of Hellenistic art throughout the Christian period, and that it maintained the highest classical standard at a time when most of the Mediterraneancountries were already submerged in what are commonly called the Dark Ages. This theory has, however, been contested by other writers who think that Alexandrian art sank as early as the fifth century to the level of provincialism, and that from that time onwards Constantinople was the chief centre in which the classical tradition was preserved.