Task: Question Generation
Input (English): Tucson was probably first visited by Paleo-Indians, known to have been in southern Arizona about 12,000 years ago. Recent archaeological excavations near the Santa Cruz River have located a village site dating from 2100 BC.[citation needed] The floodplain of the Santa Cruz River was extensively farmed during the Early Agricultural period, circa 1200 BC to AD 150. These people constructed irrigation canals and grew corn, beans, and other crops while gathering wild plants and hunting. The Early Ceramic period occupation of Tucson saw the first extensive use of pottery vessels for cooking and storage. The groups designated as the Hohokam lived in the area from AD 600 to 1450 and are known for their vast irrigation canal systems and their red-on-brown pottery.[citation needed]
Output (English): How long ago were Paleo-Indians known to be in the Tucson area?