Early Byzantine countries experienced a successful transition from ancient society to medieval society. In order to find a stable form of rule in the general chaos and turmoil, Byzantine emperors made many attempts, among which the reforms of Constantine I and Justinian I (reigned from 527 to 565) were outstanding representatives. Justinian I spent his whole life trying to revive the former glory of the Roman Empire and restore its vast old borders. His efforts are doomed to failure, because the era of seeking to establish a new order under the framework and system of the old society is gone forever. After the death of Justinian I in 565, the Byzantine Empire fell into a crisis of internal troubles and foreign invasion, with constant coups and foreign invasion, barren farmland, shrinking cities and population, especially the siege of Slavs, Avars, Persians, Arabs, Lombardi and other neighboring nationalities, which further aggravated the situation.
In 6 10, Chirac I (6 10-64 1 reigned) ascended the throne of the Byzantine Empire, marking the beginning of Byzantine medieval history. During this period, in order to speed up the militarization of imperial social organizations, Byzantium carried out reforms centered on the military region system. This system adapted to the needs of the development of the situation at that time, effectively eased the crisis situation, and provided a strong guarantee for stabilizing the situation and enhancing national strength. On the basis of the increasing national strength of the empire, the Byzantine army based in the Balkans and Asia Minor continued to expand overseas. During the Macedonian dynasty, the Byzantine Empire reached its peak, and a series of successful foreign wars launched by Vasily II (976- 1025) became the symbol of the prosperity of Byzantine countries. However, things are changing rapidly. The military region system, which once saved the Byzantine Empire from peril, exposed a series of insurmountable contradictions in its development. The big land aristocracy developed under the military region system is becoming stronger and stronger, which is enough to resist the centralization of the empire economically and politically. The disintegration of the small-scale peasant economic base on which the military region system depended became the beginning of the decline of the Byzantine Empire. The end of Macedonian dynasty marked the end of the history of Byzantine empire and the beginning of Byzantine decline.
The late Byzantine history is the history of the empire's rapid decline until its demise. 1 1 At the end of the year, the once prosperous military region system completely collapsed, the economic strength of the empire fell sharply, and the national treasury was empty. The collapse of small-scale peasant economy with farmers and soldiers as the main body not only plunged Byzantium into economic crisis, but also exhausted its military resources. Aristocrats backed by big real estate, especially military aristocrats, participated in political affairs and competed for the throne. They killed each other and led the wolf into the room, which led to the fall of Constantinople by the Crusaders in 1204. Since then, the Byzantine territory has been divided, centralization has collapsed and the territory has been shrinking. In the end, Byzantium in its heyday became a small country in the eastern Mediterranean, struggling with Ottoman Turkey, Serbia and Bulgaria. 1453, the Ottoman Turkish Empire captured Constantinople, and the last emperor Constantine Xi (1449-1453 reigned) was killed, and the Byzantine Empire finally perished.