1. Ban Gu, Western Han Dynasty, The Books in the Former Han: The Commentaries of the Western Regions, Vol. 2, Fascicle No. 69 (in Chinese), about 100 A.D.
2. Yang Xuanzhi, Northern Wei Dynasty, Travels of Jialan, Luoyang, Vol. 5 (in Chinese), about 530A.D.
3. Li Daoyuan, Northern Wei Dynasty, The Commentaries of Water Resources: The Part of the Rivers Vol, 2 (in Chinese), from the end of 5th centary to the beginning of 6th century.
4. Fa Xian, Northern Wei Dynasty, Travels in the Buddha Kingdoms (in Chinese), about 420 A.D.
5. Xuan Zang, Bian Ji, Tang Dynasty, Travels in the Western Regions Tang Dynasty, Vol. 12 (in Chinese), 640 A.D.