The first Americans crossed into North America over a land bridge that connected Siberia to Alaska around 30,000 years ago during the last ice age. As the climate warmed, sea levels rose and the land bridge disappeared. These early peoples adapted to various environments across North and South America, developing distinct cultural practices and traditions depending on available natural resources and climate conditions in different regions. Though cultural practices varied regionally, Native Americans generally shared beliefs about nature's spirituality, communal land ownership, and sustainable use of resources.