With more than 30,000 types of ancient coins from different stages of Chinese history, Xiji county in the Ningxia Hui autonomous region is widely accepted in the academic world as the richest trove in the country.
The Xiji County Coin Museum has more than 200,000 coins used from the Xia Dynasty (c. 21st century BC-16th century BC) until today and presents the full story of coins in China.
The museum, located in western Ningxia, was established in 1996. It is China's first county-level museum.
One of its most precious relics is the qianlongbao, a type of coin produced by the Xinjiang Coin Bureau during the Qing Dynasty (1644-1912). It is listed as a national first-class cultural relic.
Bai Xiaolong, head of the museum, said coins reflect the politics of their day.
"If a country is unified and stable, the coins of the regime or dynasty are unified, such as the dynasties of the Han, Tang, Song and Ming," Bai said.