The major factor in the decline of the Byzantine Empire was the constant military invasions and attacks from various outside forces, including the Seljuk Turks, Crusader armies, and Ottoman Turks. This constant pressure on the empire's borders weakened its defenses and financial resources, ultimately leading to its downfall. Additionally, internal political and social unrest, such as rebellions, power struggles, and economic issues, also played a role in the decline of the Byzantine Empire.
