New study suggests rise of ancient city Tiwanaku coincided with major volcanic event in Lake Titicaca Basin's vicinity.

A massive volcanic eruption may have helped to set in motion the development of one of South America’s earliest complex societies. 

Experts have identified ashy layers at multiple Bolivian sites as tephra, a material produced by volcanic eruptions, that rained down on settlements near Lake Titicaca sometime between 400CE and 720CE—a period that coincides with the rise of the ancient city of Tiwanaku.

“We suggest that this tephra represents a major eruption that may have played a significant role in the histories of human-volcano interactions in the region,” write Erik J. Marsh of the National Scientific and Technical Research Council, Argentina, and Christopher J. Harpel and David E. Damby of the US Geological Survey, in an article published in the journal The Holocene.