Revelations from Patch 4.3

[Keever]

I've always thought Dalmasca is around here

It absolutely is.

The Dalmasca Desert is a vast wasteland in the southern reaches of central Othard, sharing an eastern border with Nagxia. So large is the desert that it is divided into two regions, the Estersands and the Westersands.

The lorebook contains some contradictory information about the location of Dalmasca, as well as some contradictory information about the year of its fall to Garlemald. It's one of those pesky errors that this forum compiled a big thread about. The Wandering Dramaturge's dialogue is likely our most reliable source at this point.