In the four decades since mysterious terra-cotta statues first came to light in northern China, archaeologists have uncovered a whole lifelike army. But that wasn't the only secret hidden underground there. Stunning revelations are now rewriting the history of the great ruler who created this army as part of his final resting place. And a radical new theory even suggests that foreign artists trained his craftsmen.

Known today as the First Emperor, Qin Shi Huang Di left a legacy that would make him a towering figure in Chinese history. By the time he died in 210 B.C., he had united warring kingdoms into one country, put an end to feudalism, and built the Great Wall that endures today as a monument to his power.

China's Terra-Cotta Warriors

The explore team visits the tomb of the Terra-Cotta Warriors and Horses, where there is a ceramic army of as many as 8,000 life-sized, intricately carved statues modeled after Emperor Qin's army.

But his most stunning project first came to light in 1974 when farmers uncovered strange figures while digging a well near the old Chinese capital of Xianyang. Excavations have since revealed sections of a grand funerary complex. Three huge pits harbor several thousand warriors, presumably meant to protect the emperor for eternity. These statues were unlike anything ever uncovered before in China. And that raises a big question: How could the royal artists have come up with such an idea?

Experts identify these terra-cotta figures as acrobats. Some believe the sculptures' lifelike details are evidence of Greek artistic influence.

Scientists have gathered a variety of provocative clues: Terra-cotta acrobats and bronze figures of ducks, swans, and cranes uncovered at the royal tomb complex may show evidence of Greek influence. And European DNA has been recovered from skeletons at a site in northwestern China.

Putting these together, experts have worked out a theory: Inspiration for the terra-cotta army may have come from foreign artists. Traveling from Hellenized areas of Western Asia and arriving in China 1,500 years before Marco Polo, they could have trained the local craftsmen who furnished the emperor's tomb with statuary. (Learn more about how the terra-cotta warriors were made here.)

China's Megatomb Revealed

Scientists using remote sensing, ground-penetrating radar, and core sampling have also revealed the emperor's tomb complex to be much larger than once believed—almost 38 square miles (some 98 square kilometers). At its heart stands a tall earthen mound that covers the ruler's tomb, which remains sealed. Many other people were also buried at the site. Archaeologists have discovered mass graves that appear to hold the remains of the craftsmen and laborers—including convicted criminals in chains—who died during the three decades it took to create the royal mausoleum. Other mass burials seem to tell grisly tales of a brutal struggle to capture the emperor's throne.

Chinese Game of Thrones

Despite the brilliance and power of the First Emperor, he was unable to make sure his eldest son succeeded him. It was a failure that had devastating consequences. Experts now believe it may have launched a bloodbath—and ultimately brought a swift end to the dynasty that Qin Shi Huang Di founded.

An account written in about 89 B.C. by Sima Qian, an official in the second dynasty, describes a time of deadly palace intrigue: One of the emperor's many sons conspired with the chief eunuch to murder his oldest brother, the emperor's presumed heir, and to seize the throne himself.

Now archaeologists have found tantalizing clues that the power grab was even more brutal than Sima Qian described. A group of skeletons was found with artifacts belonging to the royal family. These were mostly males, possibly the deceased emperor's sons. One skull offers clues to their fate. It's split by the metal bolt from a crossbow, likely shot at close range. Experts now believe these young princes may have been executed by their ambitious sibling who was trying to secure the throne for himself.

A metal bolt shot from a crossbow remains lodged in this male skull. He may have been a prince who was murdered in a bloody struggle for his father's throne.

In another area, very close to the emperor's burial, archaeologists have identified a group of about a hundred tombs. But after excavating several, they're still unsure of what they've found. The burial chambers are empty, and body parts lie strewn in the doorways along with a scattering of pearls and pieces of gold. Were these the royal concubines, buried near the deceased emperor to serve him in the next world as they had in this life? Or do these graves represent something sinister?

According to the account left by Sima Qian, the new emperor—the usurper—killed many of his father's concubines. Sad as it may seem, that move would have made sense to someone whose claim to the throne was shaky. The usurper had already killed the heir apparent and also likely did away with other brothers who were potential rivals. But what if some of the concubines were pregnant? And what if one were to give birth to a boy who was then hidden, brought up in secret, trained to be a great warrior, and finally presented as a fully grown man able to overthrow his much older brother and take their father's title and territories for himself?

In thinking through this worst-case scenario, there would have been no choice. The women had to die. But why their bodies were dismembered is unclear. Perhaps clues will turn up in the many burials that are still to be excavated.

The skull and leg bones of a young female are likely the remains of a concubine found near the emperor's burial.

In the end, though, all the bloodshed was for naught. The usurper, Qin Er Shi, couldn't begin to fill his father's shoes. His rule lasted a mere three years, and his family's dynasty was soon overthrown. The first emperor's tomb surely holds many more surprises, but archaeologists have no plans to excavate it in the near future. Exposing fragile artifacts to air and light might damage them beyond repair, it's feared, so the tomb will most likely stay buried until radically new conservation technologies are discovered in the future.

Sima Qian wrote that the emperor was laid to rest in a bronze coffin, and his burial chamber was filled with lavish grave goods—replicas of palaces, rivers of mercury, "rare utensils and wonderful objects." But Sima Qian was writing more than a century after the first emperor's death. Could he really have gotten all the details right?

Some of his statements seem too over the top to be true—that the emperor pressed 700,000 laborers and convicts into service to build his grand funerary landscape, for example. And Sima Qian seems to have skipped over some important features altogether, offering not one word about the creation of the terra-cotta army.

But in light of the evidence for royal murders before the unlikely succession of a very junior prince, it seems entirely possible that his description of the royal burial chamber is accurate—and that archaeologists will someday uncover Qin Shi Huang Di's fabled trove of treasures.

China's Megatomb Revealed airs in the U.S. on Sunday, October 23, at 9/8c and globally on National Geographic Channel (excluding the UK) beginning Sunday, October 16.