Theoretically, they Chinese could march to Iran via Pakistan, or base fighters there, but I just don't see that happening.
Extremely theoretically. No roads, no railroads, no supply lines, no rice, army starves to death. It would take the Chinese 20 years to build a logistics supply line overland to Iran starting at the Chinese border.
Far easier to go by sea. Except for the fact that they have to pass by India, which is unfriendly to China, sitting right there athwart China's supply lines. The Chinese aren't ready to challenge the Indian Navy in the Indian Ocean, much less the U.S. Navy.
Extremely theoretically. No roads, no railroads, no supply lines, no rice, army starves to death. It would take the Chinese 20 years to build a logistics supply line overland to Iran starting at the Chinese border. As I said, I don't see it happening, but for an example of how it would be done, see "Alexander the Great".