Why did the Roman Empire last longer in the east

the Roman's split the empire in two the East And West since the country was to big to rule by few people the west had the capital of rome while the east had the captial of Istanbul. in the West we will call them Roman's while in the east we will call them Byzantines. in the west the Roman's had more significant problems such as revolts and invasions from the Germanic Tribes which eventually overwhelmed the Roman's which caused them to fall a other major cause is economic downfall as the romans were fighting in so many wars at that time they couldn't even pay thier soldiers properly. in the east the byzantines were fighting a war with the persians and keep in mind they were still part of the Roman empire just split up until rome fell then they became the byzantium empire. anyways in the east they had rebellions but not major ones and they also had other Nations around them but most of them never posted a threat except for Persia a other significant cause is that byzantine was mostly never under threat and were basicly in only one war against Persia unlike rome which were against multiple after rome fell byzantium empire was born they took back rome for a while then lost it and kept losing land to revolts and tribes around the middle east then the ottomans came and killed em basicly in the 1400's