中古時期之粟特胡及其影響唐蕃關係之研究

The Sogdians in the Middle Ages and their Impact on the Relation between the Tang Dynasty and Tibet

粟特胡於西元七、八世紀活躍於亞洲東半部的農牧地區，掌控了東西貿易，同時為便於經商獲利，介入亞洲東半部的農牧政權內部，以其長年來往於東西各地，具備廣博的知識，以及對各地政治的敏感度，試圖發揮其影響力，以獲取掌控東西貿易之利。其先後於突厥、回紇等北亞游牧政權擔任政治顧問，亦曾作為政治使節或軍事將領來往於東西南北各國之間；俟突厥勢弱，彼等亦大量徙居於唐朝，爾後造成安史之亂，唐朝國力為之中衰；回紇乘此時機崛起，亦得到粟特胡的襄助，於唐回之間興起絹馬交易，從中獲利，並改變了唐回關係的內涵。凡此，說明了粟特胡的活動，影響了中古時期農牧政權間關係的演進。吐蕃於李唐安史亂作之時，侵佔李唐河西、隴右之地，佔領絲路東段，改變了當時唐蕃間的形勢，吐蕃一躍成為主宰亞洲東半部農牧地區的力量。本文主旨在於探求粟特胡究竟在唐蕃互動關係之中，是否扮演著有如促進李唐與突厥、李唐與回紇之間關係演化的角色？粟特胡是否一如進入突、回汗廷般，也進入吐蕃王廷，活躍於吐蕃的政治與文化舞台？因為既然粟特胡足跡遍及歐亞內陸，為何獨漏與李唐、大食、突回等同屬歐亞內陸強權的大國──吐蕃？

The Sogdians circa 7-8th century was active in the arable and grazing regions of the eastern part of Asia and took control of the east-west trade. They, meanwhile, intervened in the nomadic regimes of the eastern part of Asia in order to obtain advantages in business. Sogdia's long term contact with the east and the west helped them gain broad knowledge and possess sensitivity to politics in each area. It resulted in Sogdia's attempt to spread its influence so as to earn profits via the east-west trade. The Sogdians successively served as political consultants to the nomadic regimes in northern Asia such as Gök Türk and Uighur. They have also dispatched political envoys or high-ranking military officers to cope with neighboring countries. When Gök Türk became weak, the Sogdians took the chance to migrate to the Tang Dynasty's domain. The mass migration eventually triggered the Rebellion of An Shi which brought about the decline of the Tang Dynasty and the rise of Uighur. The Sogdians in the meantime promoted silkhorse trade between Tang and Uighur and earned profits from it. The trade simultaneously changed the connotation of relationship between Tang and Uighur. This is an example that demonstrates how Sogdia's activities influenced on the relationship among the nomadic regimes in the Middle Ages. Tibet during the An Shi Rebellion occupied Tang's He-xi and Long-yo areas and controlled the Silk Road's eastern section. Such invasion changed the situation between Tang and Tibet and led Tibet to become the dominator in the nomadic regions of the eastern part of Asia. This article mainly investigates if the Sogdians did play a decisive role in the interaction between Tang and Tibet as it did in fostering Tang-Gök Türk and Tang-Uighur relations. Did the Sogdians enter Tibet's imperial court and participate in political and cultural activities of Tibet as it did in Gök Türk and Uighur? Since the Sogdians has left footprints all over Eurasia's inland, is it fair to say that they did not appear in Tibet, a great power in inland Eurasia as the Tang Dynasty, Tazi, Gök Türk, and Uighur etc.?