The Three Kingdoms Campaign is based around the “Lakelands” hexcrawls written by Andrew Hamilton, (see https://callsignfivealpha.blogspot.com/p/old-school-rpg.html for links).
The initial campaign area is roughly L shaped, covers about 12,500 sq miles and is bounded by a large lake to the west and mountains to the south and east.
Formerly comprising three human kingdoms, after “The Shattering”, the area has became a borderland, with small settlements scattered amongst wilderness areas, with many monsters, particularly gnolls moving into to the vacuum and now competing with humans for control of the region.
The Elven Court to the east and the Southern Clan Holds are demihuman lands bordering the area.
The Lakelands Valley is located in the southern hemisphere of the world. This means that the cold regions are located in the south and the hot equatorial jungles, deserts, etc. are located to the north.