During the shift of relative power between two countries, the geopolitical implications of border areas often change with political and economic conditions. After the settlement of the Treaty of Nerchinsk, the eastern part of Sino-Russian border had witnessed peace for about one hundred years. The turning point came after the middle of the 19^th century, when the Tsarist Russia intruded into the Heilongjiang River area and expanded economically into eastern Mongolia. Hulunbuir, which stands at the intersection of the Mongolian Plateau and the Heilongjiang River area, started to face a grave security situation in the next few decades. In order to resist the threat and strengthen border defense, the Qing Dynasty started a comprehensive cultivation of Hulunbuir with new policies The sudden change of the situation in Hulunbuir is a case in point to show how the change of economy and culture influences the geopolitical situation.