Editor's Note: This article by Matthew Cox originally appeared on Military.com, a leading source of news for the military and veteran community.

FORT IRWIN, California -- Anyone who's been here has seen it: the field of brightly painted boulders surrounding a small mountain of rocks that symbolizes unit pride at the Army's National Training Center.

For nearly four decades, combat units have painted their insignias on boulders near the road into this post. It's known as Painted Rocks.