A Timeline of Chacoan history includes Chaco Culture National Historical Park, Aztec Ruins National Monument, Twin Angels Pueblo, Casamero Pueblo, Kin Nizhoni, Pierre's Site, and Halfway House. Paleo-Indian Period 11000 BC First foragers? Archaic Period 6000 BC-800 BC Hunter-gatherers 4th century CE 5th century 490 Basketmaker farming begins 6th century 500 Turquoise beads and pendants appear; offerings in great kivas (sites 29SJ423, Shabik' eshchee Village) 7th century 600-800 La Plata Black-on-White ceramic 700 Population of Chaco Canyon between 100 and 201 people 8th century 9th century 800-900 Builders use piñon, juniper, and cottonwood trees that grew close by 850-925 Large construction projects. 875-1040 Red Mesa Black-on-White ceramics 10th century 900-1150 Large buildings, mounds, roadways, great kivas, and tri-walled structures are built throughout the San Juan Basin. 900-1125 Construction of Penasco Blanco 900 Emergence of the Chaco Anasazi 900 Chetro Ketl pueblo begun 900-1025 Chaco Wash in erosional cycle and cut a paleo-channel. 925-1130 Stable environmental conditions favorable to dry farming throughout the Colorado Plateau. Human populations also stable. 950 Keet Seel, second largest cliff dwelling. is inhabited 950 Nonlocal ponderosa is the dominant beam timber; spruce and fir increase 11th century 960-1020 Unpredictable rainfall. Little building at Pueblo Bonito 1000 "Chaco phenomenon" acceleration of cultural development 1000-1075Great House construction, and roads expanded. The first usage of chocolate further than central Mexico was first used in ceramic cylinders for rituals. 1000-1140Escavada Black-on-White ceramics 1025-1090 Depositional period during which time the paleo-channel was filling. There is some historical, anecdotal evidence that the inhabitants of Chaco Canyon may have constructed a dam at the west end of the canyon. 1030Chacoans seek trees at higher altitudes 1040 Increased rainfall 1040-1050 Building resumes at Old Bonito. Pueblo Bonito construction stage II 1050-1070 Pueblo Bonito becomes more complex. Pueblo Bonito construction stage III 1050 Imports of copper bells, Macaws, and shells (origin unknown) 1054 ~July 4 - Cliff painting near Penasco Blanco consisting of three symbols: a large star, a crescent moon, and a handprint, may portray the sighting of SN 1054, the Crab Nebula supernova. 1064, 1066 Sunset Crater volcanic eruptions; volcanic debris blankets Jemez Mountains and Bandelier area. 1080-1100 Great North Road construction. 1080 Salmon Ruin established. 1080 Construction of Pueblo Alto begins. 1090 Drought 12th century 1075-1123 Pueblo Bonito constructed at Chaco. ? Five astronomical observatories are built 1100 Peak of Chaco culture. 1100-1104 Tree felling at Pueblo del Arroyo 1106-1125 Aztec Ruins