The Sea Kings

Until about a century ago, the largest polities in The Sealands were under the control of warlords referred to collectively as the Sea Kings (or Pirate Kings by disapproving observers). For much of the Sea Kings' time in the sun, the Maveren were not particularly interested in going up against them as a group—if only because Maveren don't really group well. Even after the establishment of Malfa, 350 years ago or so, clashes with the Sea Kings were mostly on a case-by-case basis.
As Malfa gained in wealth and stature, the Maveren came into direct conflict with the Sea Kings more frequently, eventually resulting in the Maveren decimating some of the Kings' territories. The remaining warlords/pirates consolidated under three Sea Kings, and things remained stable there for a little while.
A century ago or so, following increased Maveren explorations into the Aldean Ocean (part of which became the Feywaters War), tensions with the Sea Kings erupted into direct violence again. The resulting war(s) toppled the Sea Kings once and for all. In their wake, the Maveren had the opportunity to become a major sea power/pseudo-nation, but they didn't have the collective will to do it. The result is a mess of small polities and such in the islands stretching to the west from Malfa.
Some people in the western Sealands (and closer) consider themselves the descendents of the Sea Kings, and may or may not resent the Maveren because of it.