「Zhangqiujian Suanjing」《張丘建算經》is one of the masterpieces in Medieval China. China Mathematics, Shu-chun Guo (郭書春)considered those calculation problems in「Zhangqiujian Suanjing」should not be the situation of the living and taxation types in Jin Dynasty. He also confirmed the age of it should be the Pingcheng period of the Northern Wei, before the Thenthronement of the Emperor Xiaowen, based on the archival studies by modern historians Baocong Qian(錢寶琮)and Lisheng Feng(馮立升). Nevertheless, the time for the Northern Wei ‘s relocation its capital in Pingcheng(平城), so-called "the Pingcheng Period"(AD 398~494), was the first year of Tianxing of the regime of Daowu Emperor(AD398), and was overlapped by the period of Eastern Jin Longan (隆安, AD397~401)regime of Jin An Emperor (晉安帝). Therefore, my article tries to clarify archival studies during both of these two regimes which may prove certain new historical explanation for 「Zhangqiujian Suanjing」.
