text: It is also possible that the Emperor's book burning, which exempted alchemical works, could be seen as an attempt to focus the minds of the best scholars on the Emperor's quest. Some of those buried alive were alchemists, and this could have been a means of testing their death-defying abilities.
  The emperor built a system of tunnels and passageways to each of his over 200 palaces, because traveling unseen would supposedly keep him safe from evil spirits.
  Final years
  Death
  In 211 BC a large meteor is said to have fallen in Dongjun in the lower reaches of the Yellow River, and someone inscribed the seditious words "The First Emperor will die and his land will be divided" (). The Emperor sent an imperial secretary to investigate this prophecy. No one would confess to the deed, so all living nearby were put to death, and the stone was pulverized.
  During his fifth tour of Eastern China, the Emperor became seriously ill in Pingyuanjin (Pingyuan County, Shandong), and died in July or August 210 BC at the palace in Shaqiu prefecture (沙丘平台, Shāqiū Píngtái), about two months travel from the capital Xianyang, at the age of 49.
  The cause of Qin Shi Huang's death remains unknown, though he had been worn down by his many years of rule. One hypothesis holds that he was poisoned by an elixir containing mercury, given to him by his court alchemists and physicians in his quest for immortality.