I do not see any information about getting to the Mingshan and the Mogao Caves from Dunhuang.

To Mogao Caves, you can take a taxi to arrive at the cost of CNY35. By public bus, you can take local bus no. 12 at DH Hotel, Silk Road Hotel or DH Railway Station to get there directly.

You should refer to Mingsha Hill by Mingshan. Local bus no. 3 can directly take you there.

Thank you very much