The western roman empire finally collapsed due to blank

Invasions by Barbarian  tribes

parable of the tares

explanation:

in 342 bc j._c. egypt fell into the hands of the persians, under the reign of nectanebo ii

greek city-states unite in a revolt against the persian empire at the beginning of the fifth century bc. j.-c  

from the year 660 or 659 bc ad, cyrus preached the revolt against the medes to deliver the persians.