The Byzantine Empire or Byzantium is the term conventionally used by historians to describe the Greek-speaking Roman Empire of the Middle Ages, centered on its capital of Constantinople.

Having survived the fall of the Western Roman Empire during Late Antiquity, the Byzantine Empire continues to function until its conquest by the Ottoman Turks in 1453.In the context of Byzantine history, the period from about 1081 to about 1185 is often known as the Komnenian or Comnenian period, after the Komnenos dynasty.

Together, the five Komnenian emperors (Alexios I, John II, Manuel I, Alexios II and Andronikos I) rule for 104 years, presiding over a sustained, though ultimately incomplete, restoration of the military, territorial, economic and political position of the Byzantine Empire.As a human institution, Byzantium under the Komnenoi plays a key role in the history of the Crusades in the Holy Land, while also exerting enormous cultural and political influence in Europe, the Near East, and the lands around the Mediterranean Sea.

The Komnenian emperors, particularly John and Manuel, exert great influence over the Crusader states of Outremer, while Alexios I plays a key role in the course of the First Crusade, which he helps bring about.Moreover, it is during the Komnenian period that contact between Byzantium and the 'Latin' Christian West, including the Crusader states, is at its most crucial stage.

Venetian and other Italian traders become resident in Constantinople and the empire in large numbers (60–80,000 'Latins' in Constantinople alone), and their presence together with the numerous Latin mercenaries who are employed by Manuel in particular help to spread Byzantine technology, art, literature and culture throughout the Roman Catholic west.

Above all, the cultural impact of Byzantine art on the west at this period is enormous and of long lasting significance.The Komnenoi also make a significant contribution to the history of Asia Minor.

By reconquering much of the region, the Komnenoi set back the advance of the Turks in Anatolia by more than two centuries.

In the process, they plant the foundations of the Byzantine successor states of Nicaea, Epirus and Trebizond.

Meanwhile, their extensive program of fortifications has left an enduring mark upon the Anatolian landscape, which can still be appreciated today.