Kithorn is a ruined and uninhabited Riverland Keep. It is on the Eastern bank of the Silver, north of Kithorn. The Merikit slaughtered the Kencyr inhabitants, leaving only Marc, who was out hunting at the time; he, in turn, extracted a blood-price from the Merikit, killing one of them for every Kencyr they killed. The land is now claimed by the Merikit.
It is revealed in Seeker's Mask that Kithorn is a sacred site for the Merikit; the well is considered the River Snake's mouth in the Merikit religion. The Lords inhabiting Kithorn permitted the Merikit to use the site when they needed, but balked when he heard that they planned to cast a hero down the well to propriate the River Snake, because he feared contamination of his well — though no harm would have come to it. The intention of the desperate Merikit was merely to hold the Kencyr captive long enough to enact their rite — but things went wrong, there was bloodshed, and the Merikit killed the rest in a panic.