Timeline: 10,000 BC
In the early years of human history, beginning with the earliest humans about two million years ago, every place in the world was in the Stone Age, and all the people in the world got their food by hunting and gathering. For a long time, there were probably only about 2000 people in the whole world. All of these people had black skin, to protect them from the sun. All of them lived in Africa, and they lived in trees or caves or temporary shelters. Almost as soon as there were people, about 1.9 million years ago, they began to make stone tools. A million years later, around 800,000 BC, people learned to use fire.
About 65,000 years ago, probably drawn by the changing climate at the end of an Ice Age, a few of these people left Africa. They probably traveled along the coast of the Arabian peninsula, down around the coast of India, and eventually in boats to Australia. These people also had black skin.
Later on, about 50,000 years ago, different people moved out of Africa into West Asia. It was about this time that people first started to wear clothes. From West Asia, around 45,000 BC, people moved west into Europe and east towards India, Central Asia, and China. It may have been in East Asia about 40,000 BC that wolves became the first dogs, the first tame animals. A few people seem even to have used boats or rafts to reach North America and South America around 20,000 BC. As people traveled further north, their children evolved to have whiter skin, because there wasn't as much sunshine and they needed to soak up more sunshine to make enough Vitamin D to stay healthy.
About 10,000 BC there was an Ice Age. A lot of the world's water turned into icy glaciers, and so the oceans were shallower than they are now. Some places that are now underwater were above water. One of those places was the Bering Strait between Russia and Alaska, and so more people were able to cross over from Asia to North America at this time, taking their dogs with them.