The Grand Canyon region has been continuously inhabited for millennia, well before the invention of agriculture in the Americas. Early clovis peoples would have arrived following historic animal populations as they spread across the landscape. In the Grand Canyon, the lack of most megafauna inside the canyon would have forced clovis peoples to hunt the large birds, rats, and goats that inhabit the canyon even today. It's unlikely that many people lived permanently inside the canyon during this period, although it was probably inhabited during the winter.
Eventually agriculture was invented in central Mexico and spread northward to Arizona and the greater Southwest. The Grand Canyon developed agriculture relatively late for the Southwest, most likely sometime in the later basketmaker II or III eras (~500-700). People living at this time would have enjoyed very different lifestyles than their clovis ancestors. Proto-ancestral puebloan groups took advantage of the unique climate offered by the canyon. The upper rim country was cool and dry with low risk of flooding, but frigid in the winter. The deep canyon floor was wet and fertile, but hot and at high risk of floods. Natives migrated seasonally between the rim and the base of the canyon and farmed nearly year-round. People at this time mostly lived in low pithouses and relatively dispersed settlements. It wouldn't be until the Pueblo I and II eras that large scale social organization would form in the area, which constructed many of the ruins now visible today. These natives would have been large scale farmers actively participating in an immense trade network stretching from the great basin to central Mexico and beyond. They compensated for the lack of flat land in the canyon with terracing and the seasonal system of their ancestors, as well as agricultural methods unique to the canyon. There would have been numerous groups sharing the land by this point; yumans from the southwest, paiute from the north, and others. Women would have had an especially important role in canyon society, making many of the pots and material goods required for life along the cliffs.
All of this ended around the beginning of the 13th century when an unprecedented drought hit the canyon, leaving upwards of 50% of the usable land in critical drought. The causes remain somewhat unclear but the depositional record suggests a length of intense climatic variability around the medieval warm period. The subsequent collapse of other regional systems in the Puebloan heartland led to a large eastward migration to the Hopi mesas. The yuman and athabaskan groups remained in the canyon, but at much lower population densities than before. The canyon continued to be a major geographical and cultural landmark through to the present, simply without a large permanent population.
Tainer, E. M. (2010). High-Resolution Holocene Alluvial Chronostratigraphy at Archaeological Sites in Eastern Grand Canyon, Arizona.
Walpi Origin myths
Short sweet time of gods
