题目内容：

阅读下面的短文，根据短文内容，简单回答问题

Once thirty thousand years ago, people from northern Asia went to America. Today, we call these people Indians.

The Indians went to America because the weather began to change. Northern Asia became very cold. Everything froze. They had to move or die. How did the first Indians go to America?  They walked!

Later Columbus found the New World in 1492. At first, only a few Europeans followed. They traveled to America in boats. For the next three hundred years, about 500, 000 people went there. Then the number grew very quickly. From 1815 to 1915, over thirty-two million Europeans left their countries and went to the United States. The biggest groups were from Germany and Italy. These Europeans spoke many different languages. Most of them took almost no money. They went to America so that they could find a better life.