Staff members of an Omani quarry firm demonstrate ore samples during the fourth China-Arab States Expo in Yinchuan, northwest China's Ningxia Hui Autonomous Region, Sept. 5, 2019. Held in Yinchuan from Sept. 5 to 8, the fourth China-Arab States Expo attracts around 12,600 participants from 2,900 regional organizations, commerce chambers, associations and enterprises in 89 countries. (Xinhua/Li Mangmang)