Even if the war lasted for generations, that does not mean that there was constant fighting everywhere. A stretch of land could flourish peacefully for many years, while hardly a day's march away, a place repeatedly became the victim of marauding warlords.
Above all, the constant fighting prevented the emergence of larger, stable empires. The news of an area with a certain wealth was synonymous with a death sentence. Too many reckless warlords wanted their share.
Only a few trading cities were able to build up a certain stability over many years. But that was only at the expense of integrity. Somewhere, even the most ruthless warlord had to sell his prey.