Why people from Asia arrived in the americas about 15,000 years ago

Hunters of the Siberian steppes were pursuing their prey who were crossing the land bridge that leads towards The Americas. That's why these Asians were considered as some of the aboriginal Americans of the ancient era. Most likely, the hunters in Siberia might have made their way to Alaska. 15,000 years ago, there were lots of inhabitants in the central plains of America, and a lot of documents have proven it further as well. This can be a speculation and a reason why the Native Americans were dark-skinned.