What factor contributed to the decline of the Neo-Babylonian Empire? The empire became weak after numerous rebellions. The empire was in debt due to expensive building projects. The empire fell into decline after the death of a powerful leader. The empire became weak due to wars with neighboring empires.

The empire became weak after numerous rebellions. The empire was in debt as well due to expensive building projects. The empire fell into decline after the death of a powerful leader
In 539 BCE the empire fell to the Persians under Cyrus the great at the battle of opis as well.
All of these were a factor in the empires decline

I hope this helps :)