As the longest river in Asia, development of the Yangtze River (Figure 1) was a major reorganization of the river networks in East Asia, and has played an important role in the evolution of the region's topography and landscape. During the Cenozoic, the collision between the Indian and Eurasian Plates led to the rise of the Tibetan Plateau (Rowley & Currie, 2006; Wang et al., 2008), which created the current east-tilting topography of East Asia. Previous studies suggest that this marked reshaping of the topography rearranged the drainage networks of the large rivers originating on the Tibetan Plateau, including the Upper Yangtze River (Clark et al., 2004; Clift et al., 2006; Zheng , 2015). These studies hypothesized that the Upper Yangtze River used to flow southwards and drain into the South China Sea through a path parallel to the Mekong River, for example, the paleo-Red River (Clift et al., 2006). In line with this hypothesis, some studies (e.g., Clark et al., 2004; Richardson et al., 2010) further suggest a reversal of the river flow direction in the Sichuan Basin (Figure 1b): prior to the connection between the Upper and Middle Yangtze River, rivers in the Sichuan Basin used to drain westwards, joining the western part of the Upper Yangtze River before flowing toward the South China Sea. This hypothesis predicts a paleo-drainage divide on the eastern margin of the Sichuan Basin, which separated the west-and east-flowing drainage systems. Therefore, to test the above hypothesis about the evolution of the Yangtze River, constraining the incision history of the potential paleo-drainage divide between the Upper and Middle Yangtze is crucial. On the eastern margin of the Sichuan Basin, several mountain ranges from high topography, including the Daba Shan, Wu Shan, and Xuefeng Shan (Figure 1b), which present as the most likely barriers between large drainage systems. These mountains formed as products of the collision between the North China and Yangtze Cratons during the Mesozoic (Li et al., 2017; Wang et al., 2003), and no evidence indicates a significant orogenic process in the area during the Cenozoic (Hu et al., 2006). Across the mountains, the