The last major migration into Westeros came some 1,000 years prior to the reign of King Robert Baratheon. The Rhoynar originally lived beyond the narrow sea to the east, in cities along the Rhoyne River. Legends say that the warrior-queen Nymeria sailed across the sea with an army made primarily of women, in a fleet of 10,000 ships. Nymeria married Lord Mors Martell, and together they were able to defeat other rivals in order to make Martell the first Prince of Dorne.
The Rhoynar brought their own customs and their own gods. Among the unusual traditions they introduced was the adoption of the title “Prince” rather than “King,” as evinced by Prince Mors. Also, inheritance passed to the eldest child among the Dornish, regardless of gender. In the thousand years since Nymeria’s arrival, these traditions have not stretched beyond the borders of Dorne. Most Dornishmen worship The Seven of the Andals today, but a few still honour the old Rhoynish gods.