For more than 2000 years, hundreds of pyramid tombs towered over the fabled Silk Road near the ancient Chinese city of Xian, their secrets buried and largly ignored. These enormous structures, built in preparation for the afterlives of China's Emperors and other royalty, may hold riches beyond belief. Mostly still unexcavated they are slowly revealing their mysteries to archaeology.

Chinese archaeologists estimate that they are 4,500 years old. Ancient Buddhist texts and other surviving documents suggest that the monuments are over 5,000 years old. Analyzing an aerial photograph of one set of pyramids east of Xian, ancient civilization researcher and author Graham Hancock determined that their layout coincided with the constellation of Gemini. However, computer analysis found that it is what Gemini would have looked like on the spring equinox in 10,500 BC.

In 2000, China recognized that there were some 400 pyramids in the Shanxi region, to the north of Xian. Smaller than the legendary "Great White" pyramid, these ancient remains have been classified by some as burial mounds. While some of these structures do in fact serve as tombs, others suggest the earliest Chinese pyramids served a more mysterious purpose.