After the fall of the Roman Empire in 476 seals were not used so much.

After the fall of the Roman Empire, the prosperous city declined.

With the fall of the Roman Empire, the technology was lost in the West.

Since the fall of the Roman Empire, things had been slipping backward.

"Co-councils have not worked since the fall of the Roman Empire."

The area appears to have been depopulated after the fall of the Roman Empire.

But since we haven't developed time-travel yet, we'd might as well say that the cause was the fall of the Roman Empire.

Ancient history was the time from the development of writing to the fall of the Roman Empire.

For this reason, large theatrical performances disappeared after the fall of the Roman Empire.