The most brilliant of medieval civilizations was the Eastern Roman Empire,
which was divided in 395, into two parts; the Western half, ruled from Rome,
fell to the tribal Germanic peoples known as Vandals in the 5th century.
The Eastern half, known as the Byzantine Empire,
lasted for more than 1,000 years.

In their own time, the citizens of the Byzantine Empire were known as
Romaioi ( Romans ). Only in the 17th century did scholars label them,
and their empire, as Byzantine. But the Byzantine Romans differed from the
Western Romans in two major ways: they spoke primarily Greek instead of
Latin, and they were Eastern Orthodox Christians rather than
Roman Catholics Christians. The era from about 1025 to 1453 witnessed the
decline of the Byzantine Empire and its ultimate destruction. Loss of territory,
internal discord, and defeats by the crusaders were blows from which the
empire could not recover. There were new enemies in this era,
the Petcheneg and Seljuk Turks to the east and north, and the Normans
and Slavs to the west. In 1064 the Byzantines lost Belgrade to the Hungarians.
In 1071 a Turkish victory at the battle of Manzikert ended Byzantine
control in Asia Minor. Also in 1071 the Byzantines lost their last territory in
Italy to Norman invaders. Internal politics of the empire contributed to its
growing weakness. After the death of Basil II in 1025, fifteen emperors
reigned in the 56 years until 1081. The rise of Alexius I Comnenus to power in
1081 restored some stability to Constantinople. The Comensus family ruled for
the next century, until 1185. In 1054 the final schism between the churches of
Rome and Constantinople occurred led by Pope Leo IX and Cardinal
Humbert, the papal legate to Constantinople; the Roman church
excommunicated the head of the Eastern Orthodox church, Patriarch Michael
Cerularius, as the churches differed on a number of important doctrines,
including the celibacy of clergy.

The Crusades, inspired by the Roman Catholic church, undermined the power
of the Byzantine Empire even further. In 1096 the First Crusade, consisting of
about 30,000 people, converged on Constantinople before continuing on the
Holy Land. Although, Emperor Alexius I Comnenus provided supplies
for the crusaders, they, partially out of hostility toward the Eastern Orthodox
church, proceeded to raid Byzantine lands on their way to Palestine.

Tensions between the Byzantine Empire and the Holy Roman Empire were
further fueled when disagreements about trading rights in the Mediterranean
Sea led to a war with Venice in 1171, at the very time that these cup-shaped
coins showing Christ on the 'bump' and the Emperor on the inside were
issued during the reign of Manuel I Comensus ( 1143 - 1180 ) .