A Timeline of Chacoan history includes Chaco Culture National Historical Park

Chaco Culture National Historical Park

Chaco Culture National Historical Park is a United States National Historical Park hosting the densest and most exceptional concentration of pueblos in the American Southwest. The park is located in northwestern New Mexico, between Albuquerque and Farmington, in a remote canyon cut by the Chaco Wash...

, Aztec Ruins National Monument

Aztec Ruins National Monument

The Aztec Ruins National Monument preserves ancestral Pueblo structures in north-western New Mexico, United States, located close to the town of Aztec and northeast of Farmington, near the Animas River...

, Twin Angels Pueblo, Casamero, Kin Nizhoni, Pierre's Site, and Halfway House.

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 100-200 people

9th century

800-900: Builders use piñon, juniper, and cottonwood trees that grew close by

850-925: Large construction projects. (Plog)

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

San Juan Basin

The San Juan Basin is a geologic structural basin in the Four Corners region of the Southwestern United States; its main portion covers around , encompassing much of northwestern New Mexico, southwest Colorado, and parts of Arizona and Utah....

.

900-1125: Construction of Penasco Blanco

Peñasco Blanco

Peñasco Blanco is a Chacoan Anasazi great house and notable archaeological site located in Chaco Canyon, a canyon in San Juan County, New Mexico, United States.. It is an arc-shaped compound built atop the canyon's southern rim; it was constructed in five distinct stages between 900 AD and 1125 AD...

900: Emergence of the Chaco Anasazi 

900: Chetro Ketl

Chetro Ketl

Chetro Ketl is a Chacoan Anasazi great house and notable archaeological site located in Chaco Canyon, a canyon in the U.S. state of New Mexico. In the cliffs behind the ruins there are ancient stairways that lead to prehistoric roadways that connect to Pueblo Bonito...

 pueblo begun

900-1025: Chaco Wash

Chaco Wash

The Chaco Wash is an arroyo cutting through Chaco Canyon, which is located in northwestern New Mexico on the Colorado Plateau. Another arroyo known as Escavada Wash is a tributary that feeds in from the northeast, near the western end of Chaco Canyon. Chaco Wash flows northwest to become the...

 in erosional cycle and cut a paleo-channel.

925-1130: Stable environmental conditions favorable to dry farming throughout the Colorado Plateau

Colorado Plateau

The Colorado Plateau, also called the Colorado Plateau Province, is a physiographic region of the Intermontane Plateaus, roughly centered on the Four Corners region of the southwestern United States. The province covers an area of 337,000 km2 within western Colorado, northwestern New Mexico,...

. Human populations also stable.

950: Keet Seel, second largest cliff dwelling. is inhabited
950: Nonlocal ponderosa is the dominant beam timber; spruce

Spruce

A spruce is a tree of the genus Picea , a genus of about 35 species of coniferous evergreen trees in the Family Pinaceae, found in the northern temperate and boreal regions of the earth. Spruces are large trees, from tall when mature, and can be distinguished by their whorled branches and conical...

 and fir

Fir

Firs are a genus of 48–55 species of evergreen conifers in the family Pinaceae. They are found through much of North and Central America, Europe, Asia, and North Africa, occurring in mountains over most of the range...

 increase

11th century

960-1020: Unpredictable rainfall. Little building at Pueblo Bonito

1000: Chaco phenomenon.

1000-1075:Great House construction, and roads expanded (Plog). The first usage of chocolate further than central Mexico was first used in ceramic cylinders for rituals.

1000-1140:Escavada 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.

1030:Chacoans seek trees at higher altitudes

1040: Increased rainfall

1040-1050: Building resumes at Old Bonito. Pueblo Bonito

Pueblo Bonito

Pueblo Bonito, the largest and best known Great House in Chaco Culture National Historical Park, northern New Mexico, was built by ancestral Pueblo people and occupied between AD 828 and 1126....

 construction stage II

1050-1070: Pueblo Bonito becomes more complex. Pueblo Bonito construction stage III

1050: Imports of copper bells, Macaw

Macaw

Macaws are small to large, often colourful New World parrots. Of the many different Psittacidae genera, six are classified as macaws: Ara, Anodorhynchus, Cyanopsitta, Primolius, Orthopsittaca, and Diopsittaca...

s, 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

SN 1054

SN 1054 is a supernova that was first observed as a new "star" in the sky on July 4, 1054 AD, hence its name, and that lasted for a period of around two years. The event was recorded in multiple Chinese and Japanese documents and in one document from the Arab world...

, the Crab Nebula supernova

Supernova

A supernova is a stellar explosion that is more energetic than a nova. It is pronounced with the plural supernovae or supernovas. Supernovae are extremely luminous and cause a burst of radiation that often briefly outshines an entire galaxy, before fading from view over several weeks or months...

.

1064, 1066: Sunset Crater

Sunset Crater

Sunset Crater is a volcanic cinder cone located north of Flagstaff in U.S. State of Arizona. The crater is within the Sunset Crater Volcano National Monument....

 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

Pueblo Alto

Pueblo Alto is a Chacoan Anasazi great house and archaeological site located in Chaco Canyon, northwestern New Mexico, United States. The complex, comprising 89 rooms in a single-story layout, is located on a mesa top near the middle of Chaco Canyon; 0.6 miles from Pueblo Bonito, it was...

 begins.

1090: Drought

12th century

1075-1123: Pueblo Bonito

Pueblo Bonito

Pueblo Bonito, the largest and best known Great House in Chaco Culture National Historical Park, northern New Mexico, was built by ancestral Pueblo people and occupied between AD 828 and 1126....

 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 built.

1130: Pueblo Bonito is four stories tall and contains 800 rooms

1130-1180: Fifty-year drought in the Southwest. Rain and snow cease to fall. Alluvial groundwater declines, floodplain erosion occurs. Dry-farming zone reduced, crop production potential decreased. Severe arroyo cutting and depression of alluvial groundwater. Severe environmental stress.

1140–1150: Collapse of the Ancestral Puebloan culture at Chaco Canyon.

1150: Great Houses empty

1180: Sunset Crater

Sunset Crater

Sunset Crater is a volcanic cinder cone located north of Flagstaff in U.S. State of Arizona. The crater is within the Sunset Crater Volcano National Monument....

 erupts for the second time.

16th century

1539: Marcos de Niza

Marcos de Niza

Fray Marcos de Niza was a Franciscan friar. He was born in Nice , which was at that time under the control of the Italian House of Savoy....

 erroneously describes the pueblo of Háwikuh

Hawikuh Ruins

Hawikuh Ruins, or Hawikuh is a National Historic Landmark located 12 miles southwest of Zuni Pueblo, New Mexico, on the Zuni Indian Reservation...

 as the Seven Cities of Gold

Quivira and Cíbola

Quivira is a place first mentioned by Francisco Vazquez de Coronado in 1541, who visited it during his searches for the mythical "Seven Cities of Gold". The location and identity of the "Quivirans" has been much debated over a wide area, including Kansas, Nebraska, and Missouri...

.

17th century

1680-1692: The Pueblo Revolt

Pueblo Revolt

The Pueblo Revolt of 1680, or Popé's Rebellion, was an uprising of several pueblos of the Pueblo people against Spanish colonization of the Americas in the province of Santa Fe de Nuevo México.-Background:...

 of the Pueblo people against Spanish colonists in the New Spain province.

1774: Don Bernardo de Miera y Pacheco identifies the Chaco Canyon area as "Chaca" on a map. The term, a Spanish translation of a Navajo word, is thought to be the origin for "Chacra Mesa" and "Chaco".

19th century

1844: Josiah Gregg

Josiah Gregg

Josiah Gregg was a merchant, explorer, naturalist, and author of the American Southwest and Northern Mexico regions. He is most famous for his book Commerce of the Prairies.-Early years:...

 refers to the Chaco pueblos in his book Commerce of the Prairies, making its first appearance in popular culture.

1849: Lt. James H. Simpson

James H. Simpson

James Hervey Simpson was an officer in the U.S. Army and a member of the United States Topographical Engineers.-Early years:He was born in New Brunswick, New Jersey on March 9, 1813, the son of John Simpson and Mary Brunson. He graduated from the United States Military Academy in 1832 and was...

 leads the Washington Expedition, a military reconnaissance team which surveys Navajo

Navajo people

The Navajo of the Southwestern United States are the largest single federally recognized tribe of the United States of America. The Navajo Nation has 300,048 enrolled tribal members. The Navajo Nation constitutes an independent governmental body which manages the Navajo Indian reservation in the...

 lands and records cultural sites in Chaco Canyon. Illustrations created by the Kern brothers are included in a government report.

1877: Artist and photographer William Henry Jackson

William Henry Jackson

William Henry Jackson was an American painter, Civil War, geological survey photographer and an explorer famous for his images of the American West...

 participates in the Hayden Survey of the Western United States, producing maps of Chaco Canyon, but no photographs due to technical problems.

1888: Richard Wetherill

Richard Wetherill

Richard Wetherill , a member of a prominent Colorado ranching family, was an amateur explorer in the discovery, research and excavation of sites associated with the Ancient Pueblo People...

 and Charlie Mason

Charlie Mason

Charlie "Chuck" Mason was a professional ice hockey player who played 93 games in the National Hockey League. He was born in Seaforth, Ontario and played for the Detroit Red Wings, New York Rangers, and Chicago Black Hawks.- External links :...

 find the Cliff Palace

Cliff Palace

The Cliff Palace is the largest cliff dwelling in North America. The structure built by the Ancient Pueblo Peoples is located in Mesa Verde National Park in their former homeland region...

, Spruce Tree House and Square Tower House.

Chaco Canyon is surveyed and photographed by Victor and Cosmos Mindeleff of the Bureau of American Ethnology

Bureau of American Ethnology

The Bureau of American Ethnology was established in 1879 by an act of Congress for the purpose of transferring archives, records and materials relating to the Indians of North America from the Interior Department to the Smithsonian Institution...

1896: Richard Wetherill

Richard Wetherill

Richard Wetherill , a member of a prominent Colorado ranching family, was an amateur explorer in the discovery, research and excavation of sites associated with the Ancient Pueblo People...

 begins excavating Chaco Canyon

1896-1899: George H. Pepper from the American Museum of Natural History

American Museum of Natural History

The American Museum of Natural History , located on the Upper West Side of Manhattan in New York City, United States, is one of the largest and most celebrated museums in the world...

 leads the Hyde Exploring Expedition in excavating Pueblo Bonito

Pueblo Bonito

Pueblo Bonito, the largest and best known Great House in Chaco Culture National Historical Park, northern New Mexico, was built by ancestral Pueblo people and occupied between AD 828 and 1126....

20th century

1901: General Land Office special agent S. J. Holsinger recommends creating a national park to preserve archaeological sites in Chaco Canyon

1907: Chaco Canyon National Monument is established.

1928-1929: American astronomer and University of Arizona professor A. E. Douglass

A. E. Douglass

A. E. Douglass was an American astronomer. He discovered a correlation between tree rings and the sunspot cycle....

 participates in a National Geographic Society research project exploring Chaco Canyon. Using his newly invented technique of dendrochronology

Dendrochronology

Dendrochronology or tree-ring dating is the scientific method of dating based on the analysis of patterns of tree-rings. Dendrochronology can date the time at which tree rings were formed, in many types of wood, to the exact calendar year...

, Douglass dates Chetro Ketl and dozens of Chacoan sites

Expedition under Neil Merton Judd to collect dendrochronological specimens to date habitation of Chaco Canyon

1937: A Civilian Conservation Corps

Civilian Conservation Corps

The Civilian Conservation Corps was a public work relief program that operated from 1933 to 1942 in the United States for unemployed, unmarried men from relief families, ages 18–25. A part of the New Deal of President Franklin D...

 of Navajo

Navajo people

The Navajo of the Southwestern United States are the largest single federally recognized tribe of the United States of America. The Navajo Nation has 300,048 enrolled tribal members. The Navajo Nation constitutes an independent governmental body which manages the Navajo Indian reservation in the...

 stonemasons repairs Chacoan buildings in Chaco Canyon. A previous group built soil conservation devices, planted trees, and improved roads and trails.

1941: Heavy rains cause Threatening Rock to fall, destroying ~60 rooms at Pueblo Bonito

Pueblo Bonito

Pueblo Bonito, the largest and best known Great House in Chaco Culture National Historical Park, northern New Mexico, was built by ancestral Pueblo people and occupied between AD 828 and 1126....

.

1960: Floors excavated at Una Vida

1971-1982: The Chaco Project, conducted by the National Park Service

National Park Service

The National Park Service is the U.S. federal agency that manages all national parks, many national monuments, and other conservation and historical properties with various title designations...

 and the University of New Mexico

University of New Mexico

The University of New Mexico at Albuquerque is a public research university located in Albuquerque, New Mexico, in the United States. It is the state's flagship research institution...

, surveys and excavates Chaco Canyon

1976-1978: Fourteen rooms at Pueblo Alto excavated by the Chaco Project

1980: Chaco Canyon National Monument is re-named Chaco Culture National Historical Park with 13,000 acres (53 km²) added. The Chaco Culture Archaeological Protection Site program is created to protect Chacoan sites.

1982: NASA

NASA

The National Aeronautics and Space Administration is the agency of the United States government that is responsible for the nation's civilian space program and for aeronautics and aerospace research...

's Thermal Infrared Multispectral Scanner (TIMS) detects over 200 miles of a prehistoric (AD 900 or 1000) road system in Chaco Canyon, as well as walls, buildings, and agricultural fields.

1983: Dean and Warren estimate 200,000 trees were used to build great houses.

1987: Chaco Culture National Historical Park is designated a UNESCO World Heritage Site.

2001: Two-thirds of large roof timbers traced to Chuska Mountains and one-third to San Mateo Mountains.