Shandan County (Chinese: 山丹县) is a county in Gansu Province, the People's Republic of China. It is one of 58 counties of Gansu. It is part of the Zhangye prefecture, with the city of the same name being the prefecture seat. It is an important site located on the ancient Silk Road. Its postal code is 734100, and in 1999 its population was 194,901 people. It is famous for horses and pastures. Ancient Han people called the horses as heavenly western horses. Lakes provide plentiful water to the animals on the pastures.