This is something I noticed while running in observe mode to test the new compatch, so forgive the sparse details. From the title history, it appears that Sauron took all of Anorien in 3016 with a kingdom-tier holy war. Since he did not destroy Gondor with the decision, it was still around for Aragorn to come in and be crowned a few years later. Then somehow, the events that normally let Denethor keep Osgiliath and give him a new kingdom-tier Steward title gave both the county and new kingdom to Aragorn.
This is something I noticed while running in observe mode to test the new compatch, so forgive the sparse details. From the title history, it appears that Sauron took all of Anorien in 3016 with a kingdom-tier holy war. Since he did not destroy Gondor with the decision, it was still around for Aragorn to come in and be crowned a few years later. Then somehow, the events that normally let Denethor keep Osgiliath and give him a new kingdom-tier Steward title gave both the county and new kingdom to Aragorn.