These territories were home to many different cultural groups, both urban populations and rural populations.
Generally speaking, the eastern Mediterranean provinces were more urbanised than the western, having previously been united under the Macedonian Empire and Hellenised by the influence of Greek culture.
However, it was delivered a mortal blow during the Fourth Crusade, when Constantinople was sacked in 1204 and the territories that the Empire formerly governed were divided into competing Byzantine Greek and Latin realms.
As regards his economic policies in particular, he has been accused by certain scholars of "reckless fiscality", but the gold solidus he introduced became a stable currency that transformed the economy and promoted development.
Under Constantine, Christianity did not become the exclusive religion of the state, but enjoyed imperial preference, because the emperor supported it with generous privileges.
In 330, Constantine moved the seat of the Empire to Constantinople, which he founded as a second Rome on the site of Byzantium, a city strategically located on the trade routes between Europe and Asia and between the Mediterranean and the Black Sea.
Constantine introduced important changes into the Empire's military, monetary, civil and religious institutions.
This older name of the city would rarely be used from this point onward except in historical or poetic contexts.
The publication in 1648 of the Byzantine du Louvre (Corpus Scriptorum Historiae Byzantinae), and in 1680 of Du Cange's Historia Byzantina further popularised the use of "Byzantine" among French authors, such as Montesquieu.
This battle opened the way for the Turks to settle in Anatolia.
The Empire recovered again during the Komnenian restoration, such that by the 12th century Constantinople was the largest and wealthiest European city.
The West also suffered more heavily from the instability of the 3rd century AD.
This distinction between the established Hellenised East and the younger Latinised West persisted and became increasingly important in later centuries, leading to a gradual estrangement of the two worlds.
In a matter of years the Empire lost its richest provinces, Egypt and Syria, to the Arabs.