The construction of Qin Shihuang's Mausoleum started when Ying Zheng (Qin Shihuang), the first Emperor that unified China,  acceded to the throne at the age of 13, and lasted 38 years. Terracotta Warriors and Horses Pits are part of the burial pits of Emperor Qin Shihuang's Mausoleum, and a large number of Terracotta Warriors and Horses have been unearthed in the three discovered pits. Qin Shihuang's Mausoleum is one of the largest imperial tombs in the world, with unique structure and rich contents. In fact, it is a luxurious underground palace, known as "the eighth wonder of the world".