The fourth part concludes from the historical facts that geographical principles cannot demonstrate the validity of the McMahon Line but it deteriorated into the then situations on the frontier.

• 第四部分从历史事实角度充分说明：印度政府所主张的地理原则不但不能论证“麦克马洪线”的有效性，反而直接导致了中印边境局势的恶化。