1. Various European powers explored and colonized different parts of the Americas beginning in the late 15th century. Explorers like Christopher Columbus and Leif Eriksson sought wealth and trade routes but their arrivals led to widespread effects. 2. Native American populations declined dramatically due to exposure to European diseases as well as violence during European settlement and fighting over land. Europeans established profitable trade networks involving crops, commodities, and eventually slaves. 3. The interactions between explorers, colonists, native peoples, and brought people led to significant political, economic, and demographic changes on both sides of the Atlantic. It marked the beginning of sustained connections between the Eastern and Western hemispheres.