from the introduction:
So you’re an adventurer and you’ve just cleared a 6-mile hex of all threats. Now you’re looking to found your own domain. What does that involve?
This document explores domain building using the Old School Essential rules, from start (clearing land) to completion (taxation and ruling). We start with the premise that the hex that has been claimed is empty of human inhabitants and is not claimed by anyone. It is, in other words, wilderness.
These supplemental rules are focused on the higher-level play that typically focuses on the fighter or related classes, although characters of any class could conceivably found and rule a domain.