Jia Dan

Jia Dan (zh-cp|c=贾耽|p=Jiǎ Dān; 730–805)Hsu (1988), 96.] , courtesy name Dunshi (敦诗), was a Chinese scholar-official, geographer, and cartographer from Cangzhou, Hebei during the Tang Dynasty (618–907) of China.

Career

Jia worked in connection with the Honglu Office, which oversaw not only imperial funerals, but also the reception and entertainment of foreign guests and ambassadors.Schafer, 26–27.] Officials from the Department of Arms would meet with foreign envoys in order to acquire information about their native countries. This included cultural customs as well as geographic information, as a map was drawn after the geographic information was acquired from the interview.Schafer, 27.] Jia Dan became the head official for this office in the second half of the 8th century. Historian Edward Schafer states that it is no doubt that Jia's remarkable knowledge of foreign geography was derived from these interviews with foreign delegates and diplomats.

In the year 785 the Emperor Dezong had Jia complete a map of China and her former colonies in Central Asia that were lost to the Uyghurs and Tibetans.Needham, Volume 3, 543.] Upon its completion in 801, the map was 9.1 m (30 ft) in length and 10 m (33 ft) in height, mapped out on a grid scale of one inch equaling one hundred "li" (Chinese unit of measuring distance).

Written works

Jia wrote of two common sea trade routes in his day: one from the coast of the Bohai Sea towards Silla in Korea and another from Guangzhou through Malacca towards the Nicobar Islands, Sri Lanka and India, the eastern and northern shores of the Arabian Sea to the Euphrates River. Indeed, Korean vessels dominated the Yellow Sea trade, while most Japanese vessels were forced to venture towards the mouth of the Huai River and Yellow River, and even as far south as Hangzhou Bay.Schafer, 11.] Jia wrote that the ships in the Euphrates had to anchor at the mouth of the Euphrates and transfer the trade goods on land towards the capital (Baghdad) of "Dashi Guo" (Abbasid). This was confirmed by the contemporary Arab merchant Shulama, who noted that the draft in Chinese junk ships were too deep to enter the Euphrates, forcing them to land passengers and cargo ashore on smaller boats.Liu (1991), 178.] A small branch of this extensive second trade route led all the way to Dar es Salaam in Tanzania, East Africa. In his work written between 785 and 805, he described the sea route going into the mouth of the Persian Gulf, and that the medieval Iranians (whom he called the people of Luo-He-Yi) had erected 'ornamental pillars' in the sea that acted as lighthouse beacons for ships that might go astray.Needham, Volume 4, Part 3, 661.] Confirming Jia's reports about lighthouses in the Persian Gulf, Arabic writers a century after Jia wrote of the same structures, writers such as al-Mas'udi and al-Muqaddasi.

Notes

References

*Hsu, Mei-ling. "Chinese Marine Cartography: Sea Charts of Pre-Modern China," "Imago Mundi" (Volume 40, 1988): 96–112.
*Liu, Pean. (1991). 'Viewing Chinese ancient navigation and shipbuilding through Zheng He's ocean expeditions', Proceedings of the International Sailing Ships Conference in Shanghai.
*Needham, Joseph. (1986). "Science and Civilization in China: Volume 4, Physics and Physical Technology, Part 3, Civil Engineering and Nautics". Taipei: Caves Books Ltd.
*Schafer, Edward H. (1963). "The Golden Peaches of Samarkand: A study of T’ang Exotics". University of California Press. Berkeley and Los Angeles. 1st paperback edition: 1985. ISBN 0-520-05462-8.