What happened to the mysterious cliff-dwellers of Mesa Verde? For more than 700 years (600-1300 A.D.), a now-vanished community of Native Americans inhabited the cliff-sides at "Green Table," near contemporary Cortez, Colorado. Then, within the space of two generations in the late 1200s, they vanished without a trace. Today, 24 different Native American tribes in the Southwest claim to have ancestral links back to Mesa Verde.