The Paleo-Indian period covers the first original settlement of Native Americans just after their arrival on the land bridge. As I mentioned previously, there is much debate about exactly when Native Americans crossed the land bridge, so this starting point of the time period can vary depending on who you talk to. Some scientists say that Native Americans arrived in the Americas no more than 13,000 years ago, while other scientists believe that Native Americans settled and lived in the Americas well before 13,000 years ago. The Paleo-Indian period ends with major climate changes caused by the end of the ice ages, around 10,000 years ago.