re: Was the end of the Roman Republic and start of the Empire good bad for them?

There were 4 factors that collapsed the East:
1. Losing Egypt to the Muslims cut the Byzantines off from their primary food and money supply
2. Losing Asia Minor to the Turks cut the Byzantines off from their land trade routes to Asia and their main source of cavalry
3. The west opening trade with the orient eliminated the Byzantines monopoly on trade with the far east
4. Gunpowder made Byzantine walls obsolete