Craniums and Controversies of the Chachapoya Cloud Warriors
The two hundred mummies discovered at the lake were astonishingly well preserved considering how humid the region is. Scientists later discovered that the caves and crags that the Cloud People modified in mausoleums are very cold and dry microclimates, perfectly suited for long term preservation. Scores of human remains, artifacts, and biological remnants were discovered at Kuelap, including hallucinogenic plants, sacrificial animal bones, and stone weapons. Evidence of violence and fire were discovered at Kuelap, random age and gender skeletons were discovered in scattered, open locations...
Source: ancient-origins.net