What posed the biggest threat to the early peoples of the American southwest prior to the year 1300?

The biggest threat to the early peoples of the American Southwest prior to 1300 was the harsh and unpredictable climate, which included prolonged droughts and extreme temperatures. These environmental challenges significantly impacted agriculture, limiting water supply and food resources. Additionally, conflicts with neighboring tribes over land and resources further exacerbated their struggles for survival in this arid region.