Avars

The Avars are first known living in Mongolia under the rule of the Mongols, in the 400's AD. The Chinese , who lived near them, called them the Juan-Juan. When the Turks revolted against the Mongols in 552, the Avars took the side of the Mongols, and lost. After they lost to the Turks, the Avars fled to the west, and ended up in the grasslands of Russia.
When the Roman Emperor Justinian noticed that the Avars had arrived, he got the idea to pay them to fight his enemies, the Huns and the Slavs, who had been raiding Roman land in the Balkans (modern Eastern Europe). The Avars agreed, and they were able to use the Roman gold and their own military skill to conquer a large empire covering most of modern Ukraine and Eastern Europe, and in fact they themselves ended up taking over a good bit of the Roman Empire they had been hired to protect from invaders. Around 568, they also pushed the Lombards out of their home and south into northern Italy. The height of this empire was around 600 AD. In 626 AD, the Avars made an alliance with the Sassanians and attacked Constantinople itself, though their attack failed.
By the 700's, though, the Avar kings were fighting among themselves, and this civil war weakened them so much that Charlemagne and the Bulgarians were able to make an alliance and destroy the Avar empire. The end of the Avar empire was around 800 AD, and by the 870's people had stopped using the name Avar, and had been absorbed into other cultures.

Charlemagne
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