I have three questions regarding domains, settlements, and markets:
1) Assuming a settlement is a "trading station" operated by an overseas trading concern and focused on selling goods to the natives, wouldn't it Market Class be beyond its original size due to the influx of trade?
2) Do large beastman villages count as domains and settlements, maybe even with a Market Class (especially for slaves and other goods sometimes frowned upon by Lawful people)?
3) What would be the population density and settlement pattern of Isle of Dread-type tribal villages? They are probably quite centralized, but productivity of labor would be quite low due to the primitive technology. Then again, with abundant tropical rains and abundant fishing, population density might improve somewhat...
1) Yes, that's the usual method, and has been done in both ACKS products that feature markets - Dwimmermount and Sakkara. That way the "civilizing force" has access to a market with the expected resources available.
2) They can, sure. Chaotic domains. Beastmen domains are usually of a low population density, but, obviously, your campaign may vary. It'd be easy enough to alter the Market Class for only certain categories of product to emphasize/de-emphasize certain things.
3) Depends. ACKS' default is a agrarian sort of society. I know Alex has cogitated on horticultural or hunter-gatherer style domains, and I think the Patreon my be an output for that in the future.
In general I'd expect a lower population density, and perhaps you'd also drop a few lines up on total Urban Population on the pg 231 table - combine that with a centralized settlement pattern and you get a built-in barrier to larger market classes and a drop in total useful urban settlements - one larger settlement of a lesser size than usual, representing perhaps a consolidation of power and (inefficiently gathered) resources around the tribal leader.