400: Cultivation of maize (corn) begins in the American Southeastern Woodlands and soon reaches the Northeastern Woodlands. Originally domesticated in Mesoamerica, maize transforms the Eastern Agricultural Complex.
400: Ancestral Pueblo peoples of the American Southwest weave extraordinarily long nets for trapping small animals and make yucca fibers into large sacks and bags.
Scandinavians briefly settled Vinland (likely l'Anse aux Meadows on the Canadian Maritime island of Newfoundland) early in the century and perhaps ventured as far south as New England.
Pueblo people in the American Southwest evacuate most above-ground pueblos to build spectacular cliff dwellings housing hundreds of people.
The dominant Ancestral Pueblo begin gradually absorbing the Mongollon culture in the American Southwest.
Athapaskan-speaking people begin migrating from the prairies of Alberta and Montana toward the American Southwest.
The Four Corners area of the American Southwest suffered severe droughts late in the century, causing many Pueblos to abandon their cliff dwellings for irrigable settlements along the Rio Grande in southern New Mexico.
1315–1317: The Little Ice Age brought a period of severe decline to medieval Europe, causing the Great Famine.
The 14th century in America probably also brought decline of the Mississippian culture, especially in the northern states. Dendroclimatology suggests that severe droughts ravaged the American Southwest and especially the Southern Plains early in the period, leading to a rapid cultural decline.
Athapaskan-speaking people continue to migrate southward from the Canadian prairies toward the American Southwest.
Barry Gwin Williams, "Cultural Resources Overview: Lake Andes National Wildlife Refuge – Southeast South Dakota," US Fish and Wildlife Service: Region 6 – Cultural Resource Program (Jan. 2012), DOC.
Greene, Candace S. and Russel Thornton, ed. The Year the Stars Fell: Lakota Winter Counts at the Smithsonian. Washington, DC: Smithsonian Institution, 2007. ISBN0-8032-2211-4, p. 42
Johansen, Bruce E. Dating the Iroquois Confederacy.Akwesasne Notes. Fall 1995, Volume 1, 3 & 4, pp. 62–63. (retrieved through Ratical.com, 26 Oct 2009)