Why is mesopotamia also called the fertile crescent? ?

Mesopotamia, part of the region known as the Fertile Crescent in Southwest Asia, lay between the Tigris and Euphrates rivers. Every year, floods on the rivers brought silt. The fertile silt made the land ideal for farming.

from the conditions of the working class in england by friedrich engels,the main idea is :

manchester's leaders hoped to oppress its working class to benefit factory owners.