Danyang (丹陽) was a commandery of Yang Province covering the lower Yangtze and the hills to the south, in what is now southern Jiangsu and parts of Anhui. Its administration was centred in the Nanjing–Zhenjiang area.
Sun Yi, a younger brother of Sun Ce and Sun Quan, was associated with Danyang. Tao Qian, who later became Governor of Xu Province, had served in Danyang earlier in his career. The commandery was a source of troops and a strategic area for the Sun family’s hold on Jiangdong.