Fusuline faunas including 29 species belonging to 19 genera/subgenera are described from the Thitsipin Formation in eight sections/localities on the Shan Plateau in eastern Myanmar. These fusulines broadly indicate a Midian (middle Permian, Guadalupian) age. The lower diversity and the presence of some genera, such as Monodiexodina and Eopolydiexodina, suggest that the Sibumasu Block belonged to the palaeobiogeographic Cimmerian Province during the Midian. Furthermore, quantitative cluster analyses of middle Permian fusulines from the Shan Plateau and adjacent Cimmerian blocks suggest close faunal affinities between the Sibumasu Block and the Baoshan Block in western Yunnan. More importantly, widespread occurrences of fusulines Eopolydiexodina afghanensis and Jinzhangia shengi on the Shan Plateau exhibit close similarities with contemporaneous fusuline faunas from the Baoshan Block and the South Qiangtang Block but evident differences from those of the Tengchong and Lhasa blocks, which are dominated by the characteristic Nankinella-Chusenella assemblage. This faunal discrepancy provides strong evidence that the Bangong-Nujiang suture passes through the Gaoligong Orogen in western Yunnan rather than the Myitkyina ophiolites in northern Myanmar. Additionally, palaeobiogeographical analyses of these fusuline faunas from the Lhasa, Tengchong, South Qiangtang, Baoshan and Sibumasu blocks imply that the Bangong-Nujiang Ocean might have been present before the Midian.