Read the passage and answer these following question.
From a European perspective, the first explorers were engaged in the settlement and discovery of a “new world.” However, the history of the United States is but a recent episode in comparison with the history of the North American continent and its people. Between 54 million and 2 million years ago, the continent evolved into the form we know today. At least 15,000 to 20,000 years ago, nomadic hunters began to migrate from Asia across the Bering Strait.
By the fifteenth century, when the European nations were “discovering” America, the country was inhabited by a minimum of two million natives. Most of the tribes had developed some kind of agriculture or fishing while remaining as hunters and retaining nomadic characteristics. They roamed the high western plains, hunted mountain valleys, and farmed along the rivers from coast to coast. There was considerable diversity and there were several hundred different languages among the wide-ranging tribes. Several tribes, such as the Iroquois, were very successful in achieving political unity and extending their influence.
The native peoples were well adapted to their environment, and without the aid of the natives, the first European settlers might not have survived. Many native vegetables, such as maize and potatoes, became important Staples. Moreover, native trackers guided expeditions and taught hunters and explorers the ways of the land. For years, U.S. history began with Columbus, but today the cultures and contributions of the early inhabitants of the Americas are studied and acknowledged. The story of North America begins with the true origin of the continent and its peoples.