Benedict Rivers, who became King Benedict I Justman, was a knight of great repute in the Riverlands. He, supported by House Blackwood and House Bracken, defeated many petty kings, and was crowned King of the Trident. He was succeeded by his son, Benedict II Justman, who added Duskendale and Rosby to the dominion of the Riverlands.
The Justmans ruled over the Riverlands for three hundred years, until the rule of King Bernarr II Justman, the last Justman king. Bernarr's sons were murdered by King Qhored Hoare in the Guest Keep of Pyke, which was called the Bloody Keep thereafter. Bernarr launched a campaign against the Ironborn, but it was hopeless, and the Riverlands fell into anarchy. After the Storm King Arlan III Durrandon conquered the Riverlands, there were many pretenders, including Lucifer Justman, but his lineage is unproven.