Hopi Yellow Ware pottery discovered at Puerco Pueblo
Ancestral Pueblo People: Pueblo II-III-A.D. 950-1300
While most of this period was similar in climate to the present, there was a prolonged widespread drought from A.D. 1271 to 1296 (based on tree-ring data from nearby El Malpais National Monument). Although a few people still lived in pithouses, above ground rooms were becoming prominent. Subterranean ceremonial rooms called kivas were introduced. Sites expanded across the landscape. Homes evolved into above-ground pueblos, some with multiple stories. People began to make corrugated, Black-on-Red, and polychrome pottery. Tools included manos and slab metates, petrified wood and obsidian points and scrapers, and pottery that was both locally made and trade items. Artifacts link park sites to Homol'ovi, Flagstaff, the Hopi Mesas, Gallup, Zuni, and the White Mountains sites. Many petroglyphs were made throughout the Little Colorado River Valley, including solar markers. A large percentage of the recorded sites at Petrified Forest National Park belong to Pueblo II-III.
Ancestral Pueblo People: Pueblo IV-A.D. 1300 - 1450
After the drought extending into the early 14th Century, there was a period of environmental change, the return of long winters and shorter growing seasons. These conditions extended well into the 19th Century. By A.D. 1300, archeologists believe that the idea of Katsinam (sometimes spelled Kachinas) became widespread, marked by images of Katsinam in petroglyphs, pictographs, and kiva murals. Polychrome pottery became more elaborate and Glaze-on-Red was added. Piki stones (for making piki bread) became evident. Their tool kit included small triangular projectile points. The population began to aggregate into larger communities, with over a hundred rooms, kivas, and frequently a plaza, located along major drainages or near springs. By the end of Pueblo IV, most of the Petrified Forest area appears to have been depopulated, but people still used the region for a travel corridor and for resources.