Dear Laura,
Greetings from Top China Travel!
Thank you very much for your enquiry.
To be honest, it is hard to finish the tour from Xining to Zhangye, then one day tour and out on the same day.
Therefore, I suggest you at least 2 days or one more day for more places.
Therefore, May I have more information so that we could quote for you?
1) How many of you will travel together?
2) What category of hotels hope to stay in Zhangye?
3) Will you be in Xining on July 18th?
Should you have any questions, please do not hestiate to let me know.
Best regards
Sophie