From Longman Dictionary of Contemporary Englishbuffer zonebuffer zonePMan area between two armies, that is intended to separate them so that they do not fight → buffer
Examples from the Corpus
buffer zone• Each park will be bordered by a buffer zone where environmentally friendly farming will be encouraged.• Severe obesity represents a buffer zone between you and the world.• Do you really expect us to believe, as you say, that many people feel the buffer zone should be scrapped?• These buffer zones would be similar to the quiet zones around hospitals. 