Answer:
true
Step-by-step explanation:
In the 11th century the empire experienced a major catastrophe in which most of its heartland territory in Anatolia was lost to the Seljuk Turks following the Battle of Manzikert and ensuing civil war. At the same time, the empire lost its last territory in Italy to the Norman Kingdom of Sicily and faced repeated attacks on its territory in the Balkans. These events created the context for emperor Alexios I Komnenos to call to the West for help, which led to the First Crusade. However, economic concessions to the Italian republics of Venice and Genoa weakened the empire's control over its own finances, especially from the 13th century onward, while tensions with the West led to the Sack of Constantinople by the forces of the Fourth Crusade in 1204 and the dismemberment of the empire.