My first guess is because they were attacked by foreign invaders.
(but at the same time, both empires had split in their own way. The Han empire lost control and broke into different areas. The Roman Empire had become two parts, where the Western part was constantly attacked by Germanic tribes). Both sides were constantly attacked by invaders until there was no more land to take.
Because ud didn't pay attention in his mettings
Answer:
B The Number and Population of cities increased rapidly.
Because the presidency was decided by a vote he simply rigged the vote. that and he had followers i mean one man against a whole country that doesn't like him doesn't seem to hard to pick the wjnner