What ultimately contributed to the weakening of the persian empire?

The Persian Empire was weakened through weak kings.

Explanation:

During Xerxes reign as king, he was known to be hot tempered; however, not in combat. He lost many battles which weakened the Persian Empire little by little. Soon after, King Darius III runs the empire but loses three battles to Alexander the Great. Alexander the Great did preserve the government of the Persian Empire till his death in 323 B.C. Although, King Darius's defeat would mean that the Persian Empire would end.

richard nixon led the investigation that resulted in alger hiss being convicted of prejury.

i honesty don't know, good luck tho dawg