Cantrefi of Rhos
One of the lesser cantrefs of the Kingdom of Gwynedd, Rhos (which means 'moors' or 'moorland' in Welsh) is currently ruled by Chief Owain ap Edern. It consists of two lesser fortified towns, Bryn Euryn, which serves as its capital, and Caerhun.
Like most of Wales in the 5th Century, the Cantrefi of Rhos utilizes Agnatic Elective Gavelkind as its succession law: The titles of the ruler are divided among his children and the primary heir, who is elected from among the members of the ruling dynasty. The law defaults to Primogeniture. You get no Prestige penalty for having unlanded sons and can have a 30% larger demesne. Destruction of titles unader any form of Gavelkind succession is not allowed. On succession in kingdoms and empires, new kingdoms might be created for younger sons if possible. Junior heirs always get the choice to declare independence without a war. Only males can inherit.