“Ernan” (Two Souths) is the collective name of Zhou Nan (《周南》) and Zhao Nan (《召南》) in the section of Guo Feng (国风Lessons from the States) from The Book of Songs. For this special way of naming, the ancients either referred to it as “Nan Yin” (Music from the South) or extended it as an independent poetic style, but more opinions were that it denotes geographical region. In terms of research, the most reliable is the “Ernan” texts themselves. Juan Er (Field Mouseear) is the third poem in Zhou Nan. The poem contains abundant geographical evidence to show that “Ernan” denotes geographical region. The title “Juan Er” is a type of regional plant, which is most densely distributed in Qinling Mountains. Delving deep into the theme, the two expressions “Zhou Xing” (“周行”) and “Cui Wei” (“崔嵬”) in the poem are also closely related to Zhou Nan region. The two evidences are not isolated, but constitute a contradictory unity. The way taken by the male character might be the ancient Qinling maintain trail. The poem Juan Er should have been made in the south of Qinling Mountains. According to relevant literature, it can be inferred that Ernan area should refer to the middle and upper reaches of Han River, with Hanzhong (汉中) as the center.