If Theodosius had not divided the Roman Empire, I believe that the Roman Empire would not have been as corrupt and would have been stronger against it's enemies and it would stay alive longer. But, if he never did split the Roman Empire, then it would've kept growing to the point where it was too large and too hard to control, leading to Rome's fall.
I'll give you three:
China gave Japan -
Buddhism
Confucianism (the political and ethical thought)
The idea of a centralized imperial state
History is hard (I'm assuming you're in World History or WHAP) and I hope you get through it okay!
