From Pingcheng to Luoyang -- Substantiation of the climatic cause for capital relocation of the Beiwei Dynasty

摘要

Emperor Tuoba Hong of Beiwei relocated the capital from Pingcheng to Luoyang approximately 1500 years ago. Most historians speculate that his motivation was based on considerations of politics, economics, military, history, and Chinese culture. However, Sima Guang, a famous historian during the Song Dynasty, claimed 1000 years ago that cold climate was the cause of this historical event. In order to assess the credibility of Sima Guang's claim, this research examines related ancient documents and therecent frost data for a comparative study. It is found that the mean minimum temperature in Pingcheng during 479AD approx 509AD is estimated to be lower than present minimum temperature by 2.48 deg C.