The first Americans migrated to North America from Asia over 30,000 years ago during an ice age when lower sea levels exposed a land bridge. As the climate warmed, sea levels rose and the land bridge disappeared. Native Americans then adapted to different environments across North America, developing distinct cultural practices for survival. They utilized local natural resources and developed various tools, clothing, shelters, and customs that suited their environments. While cultural practices varied regionally, Native Americans generally held spiritual beliefs about nature and practiced sustainable use of resources.