夷いを以もって夷いを制せいす

expression

use barbarians to control barbarians; play one foreign power against another

A classical Chinese-derived saying, used in historical or strategic contexts. It refers to the tactic of employing one group of outsiders to subdue another, often with a connotation of cunning statecraft.

• 古こ代だい中ちゅう国ごくの王おう朝ちょうは、夷いを以もって夷いを制せいすという戦せん略りゃくをよく用もちいた。

  Ancient Chinese dynasties often employed the strategy of using barbarians to control barbarians.

• この外がい交こう政せい策さくは、夷いを以もって夷いを制せいすの考かんがえ方かたに基もとづいている。

  This foreign policy is based on the idea of playing one barbarian state against another.