Yarlung-Zangbo Ophiolite Zone (YZOZ) is classically believed to be YarlungZangbo Suture Zone (YZSZ) between indian and Asian Plates, and Triassic-Cretaceous flysch in Tethys Himalayan Zone which lies just south of the YZOZ is taken as a sedimentary sequence deposited on the northern passive margin of the Indian Plate. During the Investigation in the east aside of Renbu-Kangma, we have found a large number of the basic ultrabasic rocks which were as “no foot” wrapped in the “flysch” and I-type granite-granodiorites which intruded in the “flysch", as well as radiolarian chert and basalt beds in the “flysch"; thus we suggest that the “flysh"developed in Tethys Himalayan Zone virtually constituted an accretionary complex called as N-Himalayan Accretionary Complex (NHAC) in this paper, and the NHAC and the YZOZ were all the remains of a same oceanic crust called as Tethys-Himalayan Ocean (THO). The former was attributed to the northward subduction of the THO and represents the main part of the Suture zone; while the latter one only represents a southward obducting remnant oceanic crust between the subduction zone and Lhasa Terrain, and constituted the southern basement and fore-ridge of the Xigaze-Sangri Fore-arc Basin. Based on the new discovery we point out that the THO was possibly formed during Middle or Early Triassic and was well developed in Jurassic. At the end of Late Jurassic, the THO began to subducting northward. The first subduction zone occurred within the oceanic crust, and the zone just along the south side of the YZOZ. The oceanic crust represented by the YZOZ between the subduction zone and Lhasa Terrain southward obducted to constitute the south part of basement and the fore-ridge of Xigatze-Sangri Fore-arc Basin. In the south side of the ridge the NHAC was developed. With southward growing of the NHAC, the subduction zone southward retrogressed, and the volcanic-magmatic arc on the middle part of Lhasa Terrain during the late Jurassic and Early Cretaceous southward migrated also into Gangdise Zone in the south part of Lhasa Terrain during Late Cretaceous and Paleocene. In Eocene the magmatic arc further migrated southward into the NHAC. By the end of Eocene or Early Oligocene the THO vanished fully and the collision between indian Plate and the NHAC began Terrain. The NHAC overthrusted onto the northern passive margin of Indian Plate to make the continuous sedimentary sequence from Paleozoic to Eocene Period on the margin involved into the foreland zone.