Short answers, pulled from the story.
The Ancestral Puebloans were an ancient Native American culture of Pueblo peoples who inhabited the Four Corners region of the United States, spanning southeastern Utah, northeastern Arizona, northwestern New Mexico, and southwestern Colorado. Their homeland centered on the Colorado Plateau and extended from central New Mexico to southern Nevada.
Anasazi is a Navajo word, anaasází, meaning "ancestors of our enemies," an exonym reflecting historical competition between the Navajo and Pueblo peoples. Contemporary Pueblo peoples view it as derogatory and prefer the term Ancestral Pueblo peoples. The word was introduced into archaeology by rancher Richard Wetherill in 1888-1889 and later adopted by Alfred V. Kidder in the 1927 Pecos Classification.
The great houses were immense multi-story complexes built at Chaco Canyon in present-day New Mexico, averaging more than 200 rooms each; some had 700 rooms. They were constructed between roughly 1000 and 1125 CE using a core-and-veneer wall technique with dressed sandstone blocks. Together the Chacoan structures required the wood of 200,000 conifer trees, hauled on foot from mountain ranges up to 70 miles away.
Current scholarly consensus points to two main pressures: Numic-speaking peoples moving onto the Colorado Plateau and prolonged climate change that caused agricultural failures, including a 50-year drought at Chaco Canyon beginning in 1130 CE. Evidence of warfare, conflict, and environmental degradation also exists, though the relative weight of each factor remains debated.
The Chaco road system is a network of eight main roads radiating from the great house sites at Chaco Canyon, running more than 180 miles (300 km) in total and more than 30 feet (10 m) wide. The largest roads were built between 1000 and 1125 CE and include the Great North Road, the South Road, and the Coyote Canyon Road, among others. Scholars debate whether their primary purpose was economic transport or ceremonial and symbolic.
Yes. Most modern Pueblo peoples, including Keresans, Hopi, and Tanoans, trace their ancestry to the Ancestral Puebloans. DNA evidence has confirmed that the ancestors of the inhabitants of Picuris Pueblo once lived in Chaco Canyon. Taos Pueblo, one of three UNESCO World Heritage Sites attributed to the Pueblos, remains a living community today.