Answer:
Stable food supply.
Social structure.
System of government.
Religious system.
Highly developed culture.
Advances in technology.
Highly developed written language.
the rise of agriculture and trade allowed people to have surplus food and economic stability.
Ancient Egypt is probably the most famous river valley civilization in human history, thanks to all the pyramids.
Step-by-step explanation:
Sorry i did the ? one after the other so plz find a way to put them together and that will be your answer. xD