Final answer:
The decline of the Byzantine Empire was caused by a combination of internal issues like economic decline and political corruption, as well as external factors such as the Fourth Crusade and the expansion of the Ottoman Empire.
Step-by-step explanation:
The decline of the Byzantine Empire can be attributed to a combination of internal and external factors. Internally, the empire faced economic decline, political corruption, and complex succession issues. Externally, the empire was constantly under attack from external forces such as Ottoman Turks.
**One** major factor in the decline of the Byzantine Empire was the Fourth Crusade in 1204. Instead of targeting the Muslim forces in the Holy Land, the crusaders attacked and looted Constantinople, causing significant damage to the city and weakening the empire further.
**Another** contributing factor was the Ottoman Empire's relentless expansion. The Ottomans captured several important Byzantine territories, including Constantinople itself, in 1453, effectively ending the empire.
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