墀祖德贊，漢史料載質為可黎可促及彝泰贊普，藏文史料載其名為惹巴僅(Ral pa can)。西藏史書稱其為吐蕃三大賢君之一，與松贊干布、墀松德贊齊名。 松贊干布為吐蕃王朝開朝奠下宏基，代表著吐蕃在西元七世紀時期的蓬勃。墀松德贊為吐蕃王朝開創盛世，威震全亞，所控疆域之廣，為藏族史上僅有，定佛教為國教，影響後世極為深遠，其代表著吐蕃在西元八世紀時期的顛峰。 然而墀祖德贊在九世紀吐蕃國勢盛極而衰的情況下，繼位為贊普，其為後世藏族史家將之與前述二賢君相提並論，所憑者為何？其在位時期，意味著吐蕃王朝的發展情況為何？其是否能確實掌控政權？宰輔情形如何？對內對外之政策為何？與當時各國，尤其是與李唐的互動情為何等等，凡此均為本文所欲一探究竟的內容。

According to Chinese Historical Materials, Khri gtsug lde btasan, whose name both 可黎可足 and 彝泰, but on Tibetan Historical Material, is Ral pa can. By Tbietan Hisotry, he is one of three great Emperor of the Bed, equal in fame with Srong btasn Sagm po as well as Khri srong lde btasn. Srong btasn sgam po is the one who laid a foundation of immense structure to the kingdom of Bod as he found an empire, it represented the flourishing state of Bod in the seventh century. Khri srong lde btsan is the one who create a prosperous age of Bod, to awe the Asian World, control the tremendous land, all of these is the only man the Tibetan hisotyr had. He made Buddhism for state Religion which influence post generations so deep, it represented the high peak of Bod in eight century. Never the less, Khri gtsug lde Btsan in the declined of the Bod to succeed btsan po, the later Tibetan Historians also put him in the fame of the two, why historians do so? Could it be mean that the developing state of Bod during his kingship? If he could hold political authority in a certainty? If he had the capacity to put every minister in the right place? How about his domestic and foreign policy? Compare to other countries, especially to the Sino-Tibetan Relation. All of these questions are main subject for the topic to explore.