Complex sentence: Unionists mostly conform with Protestants and are generally of mixed Anglo-Irish or Scots-Irish descent of which the later are descendents of settlers who migrated to Ireland in the Plantation of Ulster are claim kinship with the ancient Irish clans of northern Ireland.
Split into simpler sentences: Unionists mostly conform with Protestants and are generally of mixed Anglo-Irish or Scots-Irish descent. The latter are generally descendents of settlers who migrated to Ireland in the Plantation of Ulster and claim ethnic kinship with the ancient Irish clans of northern Ireland.