The original caravan route seems to have followed the south side. At the time of the Han Dynasty conquest it shifted to the center (Jade Gate-Loulan-Korla). When the Tarim changed course about 330AD it shifted north to Hami. A minor route went north of the Tian Shan. When there was war on the Gansu Corridor trade entered the basin near Charkilik from the Qaidam Basin. The original route to India seems to have started near Yarkand and Kargilik, but it is now replaced by the Karakoram Highway south from Kashgar. To the west of Kashgar via the Irkeshtam border crossing is the Alay Valley which was once the route to Persia. Northeast of Kashgar the Torugart pass leads to the Ferghana Valley. Near Uchturpan the Bedel Pass leads to Lake Issyk-Kul and the steppes. Somewhere near Aksu the difficult Muzart Pass led north to the Ili River basin (Kulja). Near Korla was the Iron Gate Pass and now the highway and railway north to Urumchi. From Turfan the easy Dabancheng pass leads to Urumchi. The route from Charkilik to the Qaidam Plateau was of some importance when Tibet was an empire.