It's funny. I was just thinking about Babylon as I was walking down the street today because I was thinking about the differences between the ancient civilizations on either side of the Himalayas. The Chinese irrigated from the many tributaries of the Yellow River and Western China remained fertile for thousands of years. Meanwhile, the Mesopotamians irrigated from the Persian Gulf and the salt water gradually turned the fertile crescent into a desert. This is because the Euphrates and Tigris had no tributaries and they were too unpredictable for common farmers to divert.

Then I was thinking about how Cyrus the Great conquered Babylon by diverting the Euphrates so he could get at the weakest part of the city's wall with his army. Later, a Queen who's name I forget used money from the Persians to divert the Euphrates around Babylon in order to build bridges. Before then, people had to take ferries or swim across the river.