Population Migration / Travel
Having realized that the state of Li'minar was stable and the expansion of the desert had stopped, many outsiders lost interest in the problem and instead preferred to use their resources elsewhere. So they spread out across E'ath and Nisdain, as well as the rest of the wasteland, lost many of its scholars and powerful individuals.
The migration of the outsiders after the gods had already left almost a century ago, meant that few powerful individuals were still left in and around the wasteland. The few that were left did so mostly to preserve Nisdain as a rival holy city for the faith of the world trees or because they still believed they could gain something from staying near Li'minar.