~Shoto Todoroki here~
Climate changes, fires, and rivers changed the way of prehistoric people lived.
There was a time in the past where prehistoric people changed their way of life because of climate change, the invention of fires, and the existence of rivers. All of those things changed the way prehistoric people live and shaped another period of humans living in the world.
Mostly, the study of history starts from the civilization era where people have known how to write and read. Prehistoric people are the ones who came from before the civilization era where they haven’t known yet about how to write and read. There was no written language and records before the civilization era, where prehistoric people lived. Thus, it can be said that the civilization era is where the study of history starts. It also becomes the time when climate change, rivers, and fires changed the way of prehistoric people's life.
In the civilization era, people started to plant and grow agriculture to get food supplies. Thus, it is not a surprise if people in the civilization era mostly lived in the river valleys to get water supply. They planted and grew their own food supply. They benefited the water from the river to help them plant the plants, they used fire to cook their food, and the started to make a civilization which is marked by the existence of cities, governments, social distinctions, artistic expression, and religion.
Hope this helps :D