The ghouls northeast of module D1

ST17 is a dual-hex region on the D series hexagonal map that marked where, in the GenCon XI tournament, lived a nest of ghouls with sufficient oversupply to extend troops for "the Drow". These are accompanied by ghasts, intelligent stinky ghouls; the ghasts may, in turn, accompany drow "mixed" patrols in the encounters. The tournament map - which I assert was identical with the D1 module map - had space for plenty of monster lairs. The main lair of ghouls was, in effect, an Out-Take.

First, let's ask if the ghouls (and ghasts) were intrusive entirely. Ghouls are classic D&D monsters, ghasts having joined in the AD&D upgrade; and both species (or strains) feature in the primary-passage encounter tables. Since the ghouls have those ghastly leaders, they have an organisation ... somewhere. And there's the Lovecraft precedent for a "kingdom of the ghouls" underground - preferably close to a human gravesite or at least battlefield. Good that their home be as close to the surface as possible. So there is no narrative reason to exclude them. There were just tournament-scope and printing-space reasons.

Gygax's tournament map being too small for the ghouls' home, it was proper that Gygax's larger map include it. The latter map further took care to keep them off the D2 side of the arc. This allowed these creepies a direct bypass right to the Vault - at least, to some Lolthian outpost thereof. That's the spider cave in module D3. Although the ghouls don't live down in that later module; they live up here, in module D1. Well, off to a side.

The strain is not that ST17 is a ghoul kingdom. The strain is when it is introduced. Because by the time the players in the campaign have their avatars meet the ghouls in the Caverns, it is too late: they have no reason (anymore?) to visit ST17.

... unless the PCs meet them randomly in the primary-passages beforehand, that is.

Hex O10 looks the obvious spot for a grisly encounter - but, I hazard, we can do better. The PCs start it all with hex D3 but I'll get to that as I work backward. My first question is ecology. Where are the Caverns' ghouls from?

They breed (if at all) by Horizontal Gene Transfer. Per canon the surface of the D series is module G3, the steading of some Fire Giants deep within a volcanic range. Doublehex ST17 is therefore not a natural human or humanoid grave. Other human(oid) adventurers would assuredly add to their ranks; one of the ghasts in the Caverns may have been a cleric in life, working in the forests. There's also a slave-trade, which the Fire Giants feed.