3.History The first immigration movement to the American continents began from Asia probably 25000years ago when Siberian tribes,in search of new hunting grounds or of refuge from pursuing enemies,crossed over the Bering 令海峡)Strait to Alaska.By1492,over10- 20million people,mistakenly called Indians(E 第安人)by Christopher Columbus,inhabited the Americas.They developed the brilliant civilizations of Aztecs(亚兹特克文化)，the Incas(印加文化)and the Mayas(玛雅文化)3. History The first immigration movement to the American continents began from Asia probably 25000years ago when Siberian tribes, in search of new hunting grounds or of refuge from pursuing enemies,crossed over the Bering (白 令海峡)Strait to Alaska. By 1492, over 10- 20million people, mistakenly called Indians(印 第安人) by Christopher Columbus, inhabited the Americas.They developed the brilliant civilizations of Aztecs(亚兹特克文化), the Incas(印加文化) and the Mayas(玛雅文化)