Final answer:
The abandonment of Ancestral Puebloan land was not caused solely by the megadrought from ~1276-1299 CE, but rather by a combination of factors including climate change, social upheaval, and migration movements, leading to joining other cultures.
Step-by-step explanation:
The statement that the megadrought from ~1276-1299 CE was the sole cause of the abandonment of Ancestral Puebloan land is false. The end of the Ancient Puebloan cultures was the result of a combination of factors. The timeframe from 1150-1300 CE was marked by significant climatic changes, including the 300 year long Great Drought. This environmental change made agriculture more difficult and may have undermined their food sources. Other stresses included insular behavior with less trade, the introduction of new irrigation techniques, social and religious upheaval, as well as external pressures from new peoples moving into the area. By 1300 CE, these accumulative factors led to the abandonment of many towns and villages by the Ancestral Puebloans. It is important to recognize that instead of vanishing, evidence suggests the Ancestral Puebloans migrated southward, joining groups that evolved into modern Pueblo cultures such as the Hopi and Zuni.