Beijing enjoys a long tradition of ivory carving, as indicated by the ivory comb unearthed in graves of the Warring States period in Huangtupo Village. Thanks to long practice, the craftsmanship of ivory carving in Beijing is improving. As part of the efforts to protect the ecology, China became a signatory of the Convention on International Trade in Endangered Species of Wild Fauna and Flora in 1980s, which prohibits trade in ivory. Hence, tourists only can appreciate ancient cared ivories at museums.