Abstract: The “Yanjing Group” metamorphic volcanic-sedimentary rock series is an important lithostratigraphic unit on the western margin of the Yangtze Block. It was originally subdivided, from bottom to top, into the Yaside, Shimenkan, Fengtongzhai, and Huangdianzi formations; however, its depositional age and tectonic setting remain controversial. In this study, we conducted systematic petrological and zircon U-Pb geochronological analyses on metarhyolite from the Yaside Formation and muscovite quartz schist from the Shimenkan Formation within the “Yanjing Group.” The results show that the metarhyolite from the middle-lower part of the Yaside Formation yields a weighted mean ²⁰⁶Pb/²³⁸U age of (789.8 ± 3.8) Ma (MSWD = 1.01), which is interpreted as its diagenetic age. The youngest group of detrital zircons from the muscovite quartz schist at the top of the Shimenkan Formation gives a weighted mean ²⁰⁶Pb/²³⁸U age of (750.3 ± 4.4) Ma (MSWD = 0.20), constraining the maximum depositional age of this formation. Integrated with regional findings, our results reveal that the original “Yanjing Group” actually comprises two packages of sedimentary formations with distinct ages and tectonic settings: the lower part (Yaside and Shimenkan formations) is Neoproterozoic, whereas the upper part (Fengtongzhai and Huangdianzi formations) is Paleozoic. Thus, the “Yanjing Group” should be disintegrated. The redefined Yanjing Group in this study includes only the lower Yaside and Shimenkan formations, with a depositional age range of ca. 800-750 Ma. It can be correlated regionally with the Chengjiang, Kaijianqiao, Suxiong, and Liantuo formations, among others, and its sedimentary-tectonic evolution corresponds to rifting. Based on the Neoproterozoic magmatic and sedimentary characteristics of the western marginal Yangtze Block, we conclude that the Yanjing Group formed in an intracontinental rift setting, representing a geological response to the breakup of the Rodinia supercontinent on the western margin of the Yangtze Block.