Imagine two well established packs of dogs (say pack R and pack D), roaming the streets. As territorial critters are wont to do, they pee on walls and prominent objects in order to mark the borders of their respective homelands.
In the areas of their territory which are disputed, one finds an abundance of “marking” because, as one group comes and goes leaving their mark, soon the other group returns to the site and, knowing that the opposition has recently been there, once again lifts their legs in defiance.
There also are other less established groups (say packs I, G and T) which weave in and out of these territories unable to make a firm claim on any neighborhood, yet marking as they go, hoping to find a block or two not sufficiently protected and therein gain strength and recognition.
Occasionally, packs R and D meet in a disputed area. Being of nearly equal strength and numbers, and imagining the injury which would most likely occur to both packs — not to mention the potential for the lesser known packs to gain strength — neither is willing to risk all out battle. At these times, the howling and snapping and marking intensify. This restrained and calculated conflict continues for an extended period of time until it is obvious that, while expending much energy and resources and occasionally drawing blood from innocent locals and passersby who are unable to defend themselves, nothing is being gained and they must silently, instinctually agree to retreat to their respective safe areas to lick their minor wounds.
In their sanctuaries they can console themselves in the fact that, while they did not make any gains in territory, they suffered only minor injuries to themselves. The only real damages were to those locals who happened to be caught in the wrong place at the wrong time and were bitten by members of both packs — not to mention the stench from the abundant marking which we must all now live with, the scent so strong and unpleasant that it is noticed by others many miles away.