Thanks to what the ancient agriculture achieved high yields?

Ancient farmers received a good harvest thanks to the nearby rivers. It was the rivers that were considered the main wealth, because they gave the people living in these territories water and fertile land. The ancients grew products that needed water, so rain was needed, which poured down from the rivers. Also, people were helped by tools of labor. Civilization was constantly evolving and with the creation of any new tool, the harvest increased.