Greeks
There were many sorts of groups. You had Italians,Greeks,Muslims,Chinese,Middle Eastern,Turkish,Indian, to name a few. Since the Byzantine Empire was so vast, this is the reason for so many different ethnic and religion groups.
Rome
The British Empire was the largest empire in history.
germoney
The Ottomans destroyed the last part of the Byzantine Empire. (Constantinople)
Peasants and serfs
The Byzantine Empire used a weapon called Greek fire, which no other group had. It was a flame thrower of some sort, but could alternately be a bomb or grenade that was thrown and burst into fire on impact.
There have been may empires throughout history. A few of them are: the Persian empire, the Parthian empire, the Roman empire, the Byzantine empire, the Mogul empire, the Ottoman empire, the Chinese empire with its various dynasties, the Egyptian empire, the Babylonian empire, the British empire, in other words, any group of people who expanded their territory and ruled under their own laws was an empire.
The Orthodox in Russia asked that the Orthodox in the Byzantine empire send some missionaries. At this point, there was no written language for the Russian people. The byzantine empire sent two scholars, who were the brothers Cyrill and Methodius, to lead this missionary movement. These two brothers were the founders of the Russian alphabet, thus why it is so similar to the Greek alphabet. This was done so that the Bible could be translated for the people of Russia.
the assyrian empire and yhe sumerian empire
Russian people are the largest ethnic group in Russia.
A group called the Turks.