Troupers of "gaoshan" opera walk along a path in Wanggou village of Yulong township in Longnan, Northwest China's Gansu province, Feb 6, 2017. "Gaoshan" opera, which originated in Yulong, has a history of about 700 years. It was listed as one of the national intangible cultural heritages in 2008. [Photo/Xinhua]