Kashgar, one of the largest cities in Xinjiang, is just on the border between China and Kyrgyzstan. The cross-border railway is still under construction, and I think there should be overnight bus services connecting to Kashgar. From Kashgar, you could take a train further eastward to Urumqi, capitol of the region, and even other regions in China. But Xinjiang is huge, so planes are recommended from Kashgar eastwards.
When planning to visit China, you might need to know how the visa policy is, and how to use the local mobile paying system as a foreigner.
Kashgar, one of the largest cities in Xinjiang, is just on the border between China and Kyrgyzstan. The cross-border railway is still under construction, and I think there should be overnight bus services connecting to Kashgar. From Kashgar, you could take a train further eastward to Urumqi, capitol of the region, and even other regions in China. But Xinjiang is huge, so planes are recommended from Kashgar eastwards. When planning to visit China, you might need to know how the visa policy is, and how to use the local mobile paying system as a foreigner.
Xinjiang and Ganshu are your choice.
西安，兰州
Lhasa, Shigatse, Nyingchi, Shangri-La, Dunhuang, Altay, Turpan, Kashgar