I cover this briefly in this recent answer – in short, by the time anyone from China had an interest in Baktria as a region, the Greco-Baktrian kingdom had been overrun by the Yuezhi and Skythians. However, the region of Dayuan in the Ferghana Valley, which was either a rebelled portion of the kingdom or its northernmost remnant after the Yuezhi conquest, did have more regular contact with the Han after it established dominion in the Tarim Basin, and was forced into vassalage through the 'War of the Heavenly Horses' in 104-101 BCE. As for the Indo-Greek kingdom, it would have been too geographically remote.