Hey there!
The Fertile Crescent was where ancient civilizations in places like Mesopotamia by the Sumerians and other peoples conquered and created towns. This was mainly because of the rich, fertile, soil, that allowed lots of food surpluses along with riches and fortune. The soil allowed for good farming, so processing and creating food was also allowed.
The reason it was fertile was because of two rivers that surrounded the crescent: the Tigris and Euphrates river. Although some argue the Euphrates is more impactful, they both often flooded and their waters kept the soil suitable for farming.
Hope this helps!