When Rome split near the end of its existence why did the West fall when the East survived a thousand years longer?

Byzantine empire and trade.

Explanation:

The East survived a thousand years after the fall of the Roman Empire as the Byzantine Empire began to emerge. Constantinople became the capital city of the Roman Empire until the Byzantium Empire came in existence in 324 AD. The East survived for thousands of years until it conquered by the Turks in 1453. The geographical condition helped the East Empire to survive. The region provided a harbour and surrounded by the sea which offered a natural defence from invaders. Trade flourished which provided wealth and goods to the East Empire.

d: social contract theory

they thoght they were going to nuke each other