Hambry/Mejis, where most of The Dark Tower: Book IV: Wizard and Glass takes place, is further east than Gilead-that-was. It may be on the Rat-Fish beam, or between the Lion-Eagle beam and Rat-Fish beam. We don't know. All-World is a big place. More @Wikipedia
Hover over any link to get a description of the article. Please note that search keywords are sometimes hidden within the full article and don't appear in the description or title.