the.com/buffer zone

means A neutral strip of space or time deliberately kept between two parties so they don't collide, directly or diplomatically.

from "Buffer" comes from the old verb "buff," meaning to cushion or absorb a blow — which is exactly what train buffers did, those spring-loaded pads bolted to rail cars in the 1800s so carriages wouldn't smash into each other at the coupling. By the early 20th century, diplomats and mapmakers borrowed the image wholesale: a "buffer state" was a small nation wedged between two larger rivals to absorb the shock of their ambitions, the way a rail buffer absorbed the shock of steel on steel. "Buffer zone" followed naturally, stretching the same metaphor from countries to any gap — political, physical, or personal — kept on purpose so two forces never quite touch.