The Egyptians weren't the only civilization to build pyramids. Centuries later the Mayans were building their own pyramids in Central and South America.
The Mayans were known for their advances in astronomy and agriculture, and prospered from 300 AD on. But then, between 800 and 900 AD the civilization erupted into chaos and warfare. Researchers have theorized what might have brought the empire's downfall, but now they have some proof.
Scuba divers brought up some samples from the core of the "blue hole", an underwater cave in Belize.
Testing those samples revealed what many researchers have long suspected. There was a significant period of drought right around the time of the decline of the Mayan empire. That's led experts to conclude that prolonged drought is what brought about the collapse of classic Mayan civilization.