the sheer size of the newly conquered lands made it difficult to govern through the tang military garrisons. the tang emperor gaozong appointed two puppet qaghans to rule over the western turks, who were later overthrown in a rebellion that began in 662. the revolt reduced tang's western extent to beshbalik, dzungaria in northern xinjiang and ended direct tang control of central asia beyond the pamir mountains in modern tajikistan and afghanistan. the expansion of the tibetan empire from the south threatened china's hold on southern xinjiang. tibet invaded the tarim basin in 670, but tang forces regained the area in 693 and kashgar in 728, restoring the anxi protectorate and four garrisons. the conflict between tibet and the tang continued for the remainder of the tang dynasty.