Photo taken on Dec. 5, 2019 shows a terracotta warrior with stone helmet displayed at an exhibition titled "The Qin Dynasty's Unification of China" at Emperor Qinshihuang's Mausoleum Site Museum in Xi'an, northwest China's Shaanxi Province. (Xinhua/Li Yibo)

Photo taken on Dec. 5, 2019 shows an eaves tile displayed at an exhibition titled "The Qin Dynasty's Unification of China" at Emperor Qinshihuang's Mausoleum Site Museum in Xi'an, northwest China's Shaanxi Province. (Xinhua/Li Yibo)

People visit an exhibition titled "The Qin Dynasty's Unification of China" at Emperor Qinshihuang's Mausoleum Site Museum in Xi'an, northwest China's Shaanxi Province. (Xinhua/Li Yibo)

Photo taken on Dec. 5, 2019 shows a terracotta warrior displayed at an exhibition titled "The Qin Dynasty's Unification of China" at Emperor Qinshihuang's Mausoleum Site Museum in Xi'an, northwest China's Shaanxi Province. (Xinhua/Li Yibo)

Photo taken on Dec. 5, 2019 shows a terracotta warrior displayed at an exhibition titled "The Qin Dynasty's Unification of China" at Emperor Qinshihuang's Mausoleum Site Museum in Xi'an, northwest China's Shaanxi Province. (Xinhua/Li Yibo)

Photo taken on Dec. 5, 2019 shows figures of Qin Dynasty (221-207 B.C.) displayed at an exhibition titled "The Qin Dynasty's Unification of China" at Emperor Qinshihuang's Mausoleum Site Museum in Xi'an, northwest China's Shaanxi Province. (Xinhua/Li Yibo)

Photo taken on Dec. 5, 2019 shows a stone drum displayed at an exhibition titled "The Qin Dynasty's Unification of China" at Emperor Qinshihuang's Mausoleum Site Museum in Xi'an, northwest China's Shaanxi Province. (Xinhua/Li Yibo)

Photo taken on Dec. 5, 2019 shows a chime bell displayed at an exhibition titled "The Qin Dynasty's Unification of China" at Emperor Qinshihuang's Mausoleum Site Museum in Xi'an, northwest China's Shaanxi Province. (Xinhua/Li Yibo)

Photo taken on Dec. 5, 2019 shows a terracotta warrior displayed at an exhibition titled "The Qin Dynasty's Unification of China" at Emperor Qinshihuang's Mausoleum Site Museum in Xi'an, northwest China's Shaanxi Province. (Xinhua/Li Yibo)

Photo taken on Dec. 5, 2019 shows terracotta warriors displayed at an exhibition titled "The Qin Dynasty's Unification of China" at Emperor Qinshihuang's Mausoleum Site Museum in Xi'an, northwest China's Shaanxi Province. (Xinhua/Li Yibo)

Photo taken on Dec. 5, 2019 shows a chime bell displayed at an exhibition titled "The Qin Dynasty's Unification of China" at Emperor Qinshihuang's Mausoleum Site Museum in Xi'an, northwest China's Shaanxi Province. (Xinhua/Li Yibo)

Photo taken on Dec. 5, 2019 shows a terracotta warrior displayed at an exhibition titled "The Qin Dynasty's Unification of China" at Emperor Qinshihuang's Mausoleum Site Museum in Xi'an, northwest China's Shaanxi Province. (Xinhua/Li Yibo)

Photo taken on Dec. 5, 2019 shows an eaves tile displayed at an exhibition titled "The Qin Dynasty's Unification of China" at Emperor Qinshihuang's Mausoleum Site Museum in Xi'an, northwest China's Shaanxi Province. (Xinhua/Li Yibo)

A woman visits an exhibition titled "The Qin Dynasty's Unification of China" at Emperor Qinshihuang's Mausoleum Site Museum in Xi'an, northwest China's Shaanxi Province, Dec. 5, 2019. (Xinhua/Li Yibo)