Tocharians were an ancient Indo-European peoples,physically mostly European,somewhat like the Celtic people who inhabited parts of West China and probably other parts of Central Asia. They were living in organized city states around the Tarim Basin and were absorbed by the Uyghurs who invaded in the 7th century or so. In this timeline,you need to have a larger expanse of them around Tarim Basin and stronger settlements in and around the Basin to an extent that they can absorb the invaders and not the other way round as it happened IOTL. Have them have unified and strong empires and such. Try to have their original Pre Buddhist Tocharian religion develop like the Celtic/Germanic version of the Roman religion. Turkic people who invade are absorbed into this larger population of Tocharians and the rest are deflected. So how would you have this POD? Please note that I'm not replacing anyone here. I'm looking for a POD for containing an OTL invasion or diverting them Eastward here. You can think of this as a resurgent or surviving Eastern Roman Empire or Greater Armenia.