The original inhabitants of North America where the Native American tribes such as the Cherokee, Sioux, etcetera. Leif Erikson (a Viking explorer) was the first person to discover North America, and did so long before Columbus ever even sailed his ships. Later, Columbus would accidentally discover the Americas in a voyage for Portugal and Spain. The Spanish were the first to colonize what is now Mexico, the United States of America, and Canada. They were quickly followed by the Portuguese, British, and French.
It is important to note that many believe the ancestors of the Native Americans came from Asia (which is why the Asians and Natives are both Mongoloids with similar DNA), crossed a land bridge from what is now Russia in prehistoric times in nomadic tribes. They eventually adapted and settled, growing into separate nations.