Short answers, pulled from the story.
The pre-Columbian era spans from the initial peopling of the Americas in the Upper Paleolithic to the onset of European colonization, which began with Christopher Columbus's voyage in 1492. It is also called the pre-contact, pre-Hispanic, or pre-Cabraline era, the last name used specifically in Brazil. It covers the history of Indigenous cultures before significant European influence.
Asian nomadic Paleo-Indians are thought to have entered the Americas across the Bering Land Bridge, now the Bering Strait, and possibly along the coast. After an estimated 20,000-year layover on Beringia, the founding population moved south along the Pacific coast and through an interior ice-free corridor, eventually spreading across both continents.
The timing is debated. The short chronology theory places the first movement beyond Alaska no earlier than 14,000 to 17,000 years ago, while the long chronology theory proposes entry as early as 30,000 to 40,000 years ago or earlier. The Clovis culture is one of the earliest identifiable, with sites dating back roughly 13,000 years.
At its peak between the 12th and 13th centuries, Cahokia was the most populous city in North America and may have reached over 20,000 people. Located near modern East St. Louis, Illinois, its Monks Mound remains the largest earthen construction of the prehistoric Americas, though larger cities existed in Mesoamerica and the Andes.
Mesoamerica is said to have had five major civilizations: the Olmecs, Teotihuacan, the Toltecs, the Mexica, and the Maya. The Olmec was the earliest and established a cultural blueprint that later civilizations followed, while the Mexica-Aztecs ruled much of central Mexico from their capital Tenochtitlan, on the site of modern Mexico City.
Norte Chico, known in Peru as Caral-Supe, is the oldest known civilization in the Americas. It emerged on the north-central coast of present-day Peru around 3200 BCE, contemporary with the rise of urbanism in Mesopotamia, and is considered one of the cradles of civilization in the world.
Many groups collapsed largely because of Old World diseases introduced by European colonists. After Hernando de Soto's expedition in the 1540s, disease devastated Mississippian populations, and within a century nearly all those groups had vanished. The Calusa, Taino, Kuhikugu, and others suffered similar steep declines from introduced diseases.