By the time the Spanish Conquistadors arrived in the Americas, most of the large Mayan sites had been all but abandoned for hundreds of years. Most of their cities had fallen into ruin and were being overtaken by jungle. The Maya people had splintered into small villages and towns, losing the complex social strata and rituals that supported this great civilization at its apex. What caused their total extinction is somewhat of a mystery. But researchers now believe they have discovered the real cause that led to the wipe out of the Mayan civilisation. Evidence suggests the region went through a 100-year drought between the 800s and 900s, which led to internal warfare and anarchy. Scientists believe a change in a climate pattern that caused crucial monsoon rains to miss the region resulted in the drought, which subsequently led to the collapse of the civilisation.