One of my players is an Orc Shaman, ruler of a Barbarian Clanhold. Per RR pg 353:
“cannot exceed 125 peasant families per 6-mile hex”
“At no time can the number of urban families in a clanhold exceed 12.5% of the peasant population of the clanhold.”
So, if my player wants to create an urban settlement he has to invest 10k gp and move a minimum of 75 families.
According to the former…
If 75 urban families are the 12.5%, it means the domain has at least 625 families. If every 6 mile hex cannot excede 125 families, he needs at least 5 hexes.
So, does a Barbarian Clanhold need an extension of 5 hexes almost completely populated for creating the minimum populated urban settlement? Is this correct?
Yes, you’re reading it correctly. Even in traditional agrarian domains, it would be unusual to see an urban settlement when the domain is <600 families or so, and clanholds tend to have both fewer and smaller settlements. That said, once you have it, it will fill up quickly (because the growth bonus from actively raiding applies to both domain and settlement).
If for worldbuilding purposes you want to have larger urban settlements in clanholds, you can allocate the urban settlements at the realm rather than domain level - “At no time can the number of urban families in a clanhold REALM exceed 12.5% of the peasant population of the clanhold REALM.”
That would allow the chief of a powerful barbarian realm to have a substantial capital city without begging the question of “how does the capital city of Barbaria feed itself.”