Which factor contributes to the collapse of both of the Roman Empire and the Han dynasty

Wars with invaders from neighboring lands weakened both empires.

The Han Dynasty failed due to national administrative discussions among people in government and resistance form workers that were drained of heavy assessment. The Roman Empire weakened due to classes and administrative differences among the best and the extensión of its large region made challenging to control. That is why the circumstance that assigned to the destruction of both the Roman Empire and the Han Dynasty is that conflicts with enemies from neighboring lands exhausted both empires.

Both experienced social unrest and faced nomadic invasions.