Ancestral Pueblo cylinder jars are emblematic of Chaco Canyon. Only about two hundred of these vessels are known from the American Southwest; 166 come from the Chacoan site of Pueblo Bonito. Designs in black mineral-based paint on a white slip reflect styles common at Chacoan sites in the 11th century. About a third of the cylinder jars are slipped but lack painted design.
Scholars agree that cylinder vessels functioned in ritual contexts. Archaeologist Patricia L. Crown recently discovered Theobroma cacao, or chocolate, residue in shards of cylinder vessels from Pueblo Bonito. Cacao was grown in neotropical Mesoamerica and used as a beverage in elite rituals throughout Mesoamerican civilizations. The Mexica (Aztecs) used cacao beans for currency. Chaco Canyon is the farthest north cacao occurs outside the area of its cultivation. The cacao found in cylinder vessels at Chaco Canyon indicates the performance there of a specific ritual that had ties to Mesoamerica. Until this discovery, cacao had been found no further north than central Mexico.
Dr. Crown also noted that some Chacoan cylinder vesels had been re-slipped, re-painted, and re-fired. Older designs are visible through the slip, as in the vessel with the wedge-shaped designs. Re-firing pottery required a relatively great investment in fuel for Chaco Canyon, where wood was scarce. Vessels were likely cached for re-use. These vessels are two of 111 found in a single room—Room 28—in Pueblo Bonito.