Terracotta soldiers

The terracotta soldiers were thousands of terracotta statues of soldiers found in the tomb of the first Emperor of China, Qin Shi Huang.

History
Emperor Qin Shi Huangdi was promised by a Japanese wizard that he would become immortal if he followed his instructions. This included the construction of a sacred space near Xi'an, wherein the emperor, his generals, and eight thousand others would take up their positions on the seventh full moon of the year. (PROSE: The Eleventh Tiger)

The Fifth Doctor told Erimem that he delivered the Terracotta Army to the Emperor during his third incarnation. (AUDIO: No Place Like Home) At some point, the soldiers had become a mobile robot army controlled by Meng Tian's warp converter, which were waiting for the activation signal. (COMIC: The Immortal Emperor)

In 210 BC, the Second Doctor's companions Jamie McCrimmon and Victoria Waterfield discovered the Terracotta Army. (AUDIO: The Emperor of Eternity)

"A couple of centuries BC", Meng sent out the activation signal to awaken the Army so he could take control of Earth. They were stopped when Meng accidentally destroyed the warp converter in the Emperor's palace during a fight with Qin Shi Huang, which caused an explosion that buried Qin Shi Huang and the Army. According to the Tenth Doctor, the soldiers would remain statues until the excavation of the Emperor's throne room around the early 21st century. (COMIC: The Immortal Emperor)

On 27 July 1928, Edward Grainger, Carter, Ambrose and Bryce Convey tried to steal the Terracotta soldiers. While Carter and Grainger tried to take the statues by plane to Calcutta, Convey and Ambrose took the long way, getting out of China on foot. (PROSE: Falling from Xi'an)