Athabaskan languages is northwestern Canada and southern/eastern Alaska. After initial colonization, archaeologists generally divide Interior Alaska's prehistory into three broad archaeological themes: Paleo-Arctic tradition Paleo-Arctic tradition (12,000–6,000 years ago) is a term is now generally used by archaeologists to refer to the earliest settled people known from all over Alaska. In Interior Alaska, Paleoarctic tradition historically included two cultural divisions called the Nenana and Denali complexes. Nenana complex The Nenana complex was defined by W. R. Powers and John F. Hoffecker. The Nenana complex began approximately 11,000 years ago and this complex is widely regarded as part of the Palaeoindian tradition and a likely Beringian progenitor of the Clovis Complex. Many Nenana Complex archaeological sites are located in the Tanana Valley: Broken Mammoth, Chugwater, Donnelly Ridge, Healy Lake, Mead, and Swan Point. Denali complex The Denali complex, dated roughly to 10,500 to 8,000 years ago, was originally defined by F. H West. Some Denali Complex archaeological sites: Mt. Hayes, Swan Point, and Gerstle River. Both Nenana and Denali technology persist in central Alaska throughout the Holocene. The relationship between the proposed Nenana and Denali complexes is as of yet unresolved. The boreal forest in Interior Alaska (Interior Alaska-Yukon lowland taiga of Tanana region and Copper Plateau taiga of Ahtna region) was established 8,000 years ago. Two ice-age infants discovered at an ancient residential campsite (Upward Sun River site was first discovered in 2006) in Interior Alaska near the Tanana River east of Fairbanks are the oldest human remains ever found in the North American Arctic and Subarctic, and among the oldest discovered on the entire continent, according to researchers with the University of Alaska Fairbanks. Discovered in 2013, the remains of the two infants date from 11,500 years ago, near the end of the last ice age. Northern Archaic tradition The Northern Archaic tradition flourished 6,000–1,000 years ago. Site density increased again after about 6,000 years ago in Interior Alaska. This population increase coincides roughly with the Northern Archaic Tradition and the appearance of side-notched projectile points. Douglas D. Anderson originally defined the Northern Archaic Tradition to specifically address notched point bearing stratigraphic horizons that did not contain microblades at the Onion Portage site (Onion Portage Archeological District of Kobuk Malimiut tribes of Inupiat people region) in northern Alaska. Notched point assemblages occur in many sites in Interior Alaska, including over one dozen on Army's Fort Wainwright lands. Several sites,