occupied territory
Refers to land or area under military occupation. Often used in historical or geopolitical contexts.
その地域は戦時中、占領地となった。
That area became occupied territory during the war.
占領下 refers to the state or period of being under occupation, while 占領地 refers to the actual territory that is occupied.
Compound of 占領 (occupation) + 地 (land, area).