Dress in the Eastern Empire, later to be called Byzantium by the West, (although properly called Romania at the time) was directly taken from the later Roman Empire. Strictly speaking Byzantium/Romania was the late Roman Empire, although its capitol was Constantinople, and its religion predominantly Christian. The Eastern Empire continued in the Roman tradition until it was shrunk into the space of little more than Constantinople and the southern tip of Greece by successive wars with the Ottoman Turks and Western Christian countries. In 1460 the last vestige of the Eastern Empire was swallowed up into the Ottoman Empire.
Late Roman and "Byzantine" dress is more body covering than earlier Roman costume, usually including long sleeves and long hems. This is generally assumed to be a reaction to the growing Christian view that the body was not beautiful, but a pit of vice. When the tunica is shorter (only on men) the lower limbs are encased in trousers, a "barbarian" invention first adopted by the Roman army and lower classes, and eventually (after some aristocratic resistance) by all men. The toga remained for emperors and other high officials in this period, but in vestigial form as a long thin (about 6") strip wrapped round the torso in the traditional manner.
Long half circle capes were part of male court dress, worn in place of the old toga over the new long sleeved tunica. The most notable feature of the Eastern Empire's dress is its surface decoration. Unlike the earlier period which left fabric largely undecorated, the people of the Byzantine Empire used all manner of woven, embroidered and beaded surface embellishment, particularly on Church vestments and court dress. This style of decoration, and many of the garment shapes, survive to this day in the priestly vestments of Orthodox churches in Greece, Eastern Europe and Russia.