From A Wiki of Ice and Fire
The Greenblood is a river in southern Dorne and is the principal Dornish river. The river takes its name from its murky green waters which are slow-moving and shallow. It is formed by the confluence of the Vaith and the Scourge near Godsgrace. Planky Town lies at the Greenblood's mouth on the Summer Sea.
A dozen First Men houses of the Greenblood—including Houses Briar, Brook, Brownhill, Holt, Lake, Shell, and Wade—chose a High King of Dorne from amongst their number. Three of the houses were destroyed after a generation of warfare following a disputed election, however. The remaining houses were conquered during the Andal invasion, with the Shells and Wades defeated by House Martell.
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