What contributed to the emergence of new peoples on Earth?

New peoples appeared on the planet for several reasons. The first is the long life of a certain number of people in isolation from the rest. Moreover, isolation can be both natural (for example, life on an island), and deliberate. In this case, over a long period of time, this group forms its own language, behavior, culture, etc.

The second option is a mixture of two or more existing peoples. In this case, each ethnic group contributes to the formation of a new one, which may have the features of all its constituent peoples at once.