%0 Journal Article %T Spatio-Temporal Changes and Their Reasons to the Geopolitical Influence of China and the US in South Asia %A Shufang Wang %A Yuan Cao %A Yuejing Ge %J Sustainability %P 1064-1080 %D 2015 %I MDPI AG %R 10.3390/su7011064 %X The current international society has entered an era of large-scale power transfer. Government interests have gradually transferred from national strength to national influence. As such, how to quantitatively present the fuzzy geopolitical influence ( i.e., geo-influence) has attracted greater attention from scholars. The proposed concept of geo-influence conforms to this trend of power structure change in international relations, and provides a reference for national sustainable development on the international stage. This study sets up an index system and a mathematical model of geopolitical influence, and explores the spatio-temporal changes of the geo-influence of China and the United States (US) in South Asia over the past decade. Three primary results are found as follows: (1) In general, the geo-influence of China and the US in South Asia increased between 2003 and 2012. In terms of growth rate, the geo-influence of China in South Asia grew much faster than that of the US; (2) The overall strength and geo-influence show non-linear relationships. Strong national overall strength does not necessarily mean that one country has the strongest geo-influence; (3) National geo-influence is inversely proportional to the friction of distance. The larger the friction of distance is, the smaller national geo-potential is, and vice versa. %K geopolitical influence %K spatio-temporal changes %K China %K the US %K South Asia %U http://www.mdpi.com/2071-1050/7/1/1064