The Fifth World is variant setting for The Shadow of Yesterday.

In the beginning of days, the First People first emerged from the ground at the site of Kiva City. They entered the Fifth World through a small hole, led by He-Climbs-to-the-Top, the boldest of the First People of that time. The Fourth World was a lightless and watery place, and the People were scaly and black when they crawled up from under the ground. They found themselves in the hot and dry Fifth World, the sun burning in the sky. The Fifth World was a hard place, and inhabited by many monsters.

In The Fifth World, pioneering communities of the First People fight to carve out a safe haven. Their scattered communities are threatened on all sides by the monsters that infest the land, but the First People fight back, aided by secrets taught them by the Sunset People.