At that time, if Xuanzang bypassed Southeast Asia from the south, he would have to cross thousands of kilometers of tropical rain forests. If you go southwest, you will have to climb the Himalayas at an altitude of 8000 meters. It's a bit crowded along the Central Asia route.

At that time, it was basically wasteland, tropical jungle, rivers, high mountains and deep valleys and ferocious beasts after entering Hunan. Look at the map yourself. Until now, it has been difficult to take land.