The Indigenous peoples of the Americas are diverse; some Indigenous peoples were historically hunter-gatherers, while others traditionally practice agriculture and aquaculture. In some regions, Indigenous peoples created pre-contact monumental architecture, large-scale organized cities, city-states, chiefdoms, states, kingdoms, republics, confederacies, and empires. These societies had varying degrees of knowledge of engineering, architecture, mathematics, astronomy, writing, physics, medicine, planting and irrigation, geology, mining, metallurgy, sculpture, and gold smithing. (Full article...)
Since the 19th century, the prevailing scholarly consensus has been that the mounds were constructed by indigenous peoples of the Americas. Sixteenth-century Spanish explorers made contact with natives living in a number of later Mississippian cities, described their cultures, and left artifacts. By the time of United States westward expansion two hundred years later, Native Americans were generally not knowledgeable about the civilizations that produced the mounds. Research and study of these cultures and peoples has been based mostly on archaeology and anthropology.
The following are images from various Indigenous peoples of the Americas-related articles on Wikipedia.
Image 1A schematic illustration of maternal (mtDNA) gene-flow in and out of Beringia, from 25,000 years ago to present
Image 2A map showing the origin of the first wave of humans into the Americas, including the Ancestral Northern Eurasian, which represent a distinct Paleolithic Siberian population, and the Northeast Asians, which are an East Asian-related group. The admixture happened somewhere in Northeast Siberia. (from Indigenous peoples of the Americas)