Terracotta Warriors
兵马俑

The terracotta warriors are believed to be part of that plan. The Emperor believed that he was emperor of both heaven and earth. The army was intended to accompany him into the afterlife. Elaborate engineering was necessary to create an installation that would last for eternity. Underground tombs were often built like this and covered with a mound of earth. Other designs resembled caves of pounded earth hollowed out of the loess clay. This installation was beyond the usual scope of the tomb and was not intended to be covered by a mound. It is believed that the warriors and horses are only one part of a larger installation and that further segments will be found.

Notice the indentation in the wide bulwarks in the above image. Logs were placed over each section of soldiers and horses. The logs were then covered with a wooden roof and covered with pounded dirt. The installation was thus protected from the elements and for thousands of years from memory. Scientific analysis (Qing Wang, et al, 2009) has shown that the wood used was harvested locally and was primarily made up of gymnosperms, a type of pine tree. This type of analysis gives an idea of the size and scope of the project. Had the lumber been brought from a distance, the estimates of the amount of time and labor needed to complete the pits would have had to take that into account.

Wang, Qing; Zhang, Zhong-Li; Ding, Hui; Shao, Wen-Bin; Li, Cheng-Sen; Wang, Yu-Fei; Yang, Jian. "The wood in the pits of terracotta figures and its architectural application." Journal of Archaeological Science. Feb 2009, Vol. 36 Issue 2, pp. 555-561.