Dr. Allan Maca and his team explore an ancient megacity, the biggest on the planet 4,000 years ago that mysteriously disappeared - a place where the people created Maya-like carvings and humans were sacrificed on an unprecedented scale. Discovering this lost civilization changes everything known about the origins of China, prompting Dr. Allan and his team to solve the mystery.

Originally released by National Geographic, 2020. Streaming video file encoded with permission for digital streaming by Infobase on January 05, 2023.