What caused the downfall of the ancient Egyptian empire? What occurred at Angkor, the greatest kingdom in Cambodia that led to its demise? EP1: The End of the Age of Pyramids How did the most prestigious human civilizations decline and finally collapse? Archeologists are excavating the sites where these civilizations once thrived to find new answers to these crucial questions. EP2: Angkor: The Sunken Kingdom Drastic and sudden climate change, religious and political struggles, societal upheavals -- all of these causes may have led to the decline of the civilization that left behind Angkor Wat.