Hello!
Two major reasons why people stopped being nomadic are:
-farming
-domestication of animals
People were originally nomadic because they needed to constantly follow migrating animals and other food sources. People later discovered farming, and they began growing and maintaining plants. In addition, people learned how to herd and domesticate animals. With these two discoveries, people could farm and use animals as food sources without needing to continuously follow them. This was the first step to creating civilizations because people could then settle down and begin building shelters and developing a way of life.
I hope this helps answer your question! Have a great day!
