The First Bulgarian Empire, after reaching its peak under Simeon, declines in the middle of the tenth century.

Byzantine opposition and internal weakness lead to a loss of territory to the Magyars and the Russians.

Bulgaria remains economically dependent on the Empire, and the widespread Bogomil heresy opposes the secular Bulgarian state and its political ambitions as work of the devil.

Seeking to restore a balance of power in the Balkans, the Byzantines ally with the Kievan Russians under Yaroslav and invade Bulgaria several times in the late tenth century.

Although the Bulgarians expand their territory again briefly under Tsar Samuil at the end of the tenth century, in 1014 the Byzantines under Basil II inflict a major military loss.

By 1018 all of Bulgaria is under Byzantine control.

For nearly two centuries, the Byzantines will rule harshly, using taxes and the political power of the church to crush opposition.

The first and second Crusades pass through Bulgaria in this period, devastating the land.