Ottoman Turks conquering, the military system, and division
Explanation:
Justinian plague is said to have been caused by a rat bite, which killed 5,000 people in a single day. This killed half of his rule, making it easier for the armies to defeat their empire.
The barbaric attacks increased as many people died from the plague and the barbarians attacked from many places.
The Crusades were Christian warriors who tried to fight the Turks and Jews. The Byzantines were part of the Crusade, defeated by the Muslims.
Different families fought for power and many disagreements led to the decline of the government.
