Imagine that. The climate changes, and people adapt.
“...fuel for processing fires,” Wendt said. The repeated droughts at Bergstrom caused by climate fluctuations...”
Obviously the fires from this LARGE group of Ancients caused the climate to change and dried up the creek.
Or; 1,100 years ago was the Medieval Warm period so one could blame it on that.
From the web:
The Medieval Warm Period (roughly 950–1250 AD) was primarily caused by natural factors, including increased solar radiation, decreased volcanic activity (which reduced cooling aerosols in the atmosphere), and shifts in ocean circulation patterns, such as a more positive North Atlantic Oscillation (NAO) and a La Niña-like state. These factors combined to create warmer conditions, particularly in the North Atlantic and Europe, rather than a uniform global warming.