Sunspear is located on a peninsula of land just south of the Broken Arm.
A thousand years ago, Dorne was filled with petty, warring lords. When the warrior queen of the Rhoynar of the eastern continent, Nymeria, came with her people to Westeros, she took one of the strongest of the Dornish lords as husband. Lord Mors Martell, with the aid of Nymeria and the Rhoynar, conquered the rest of Dorne. Following the custom of the Rhoynar, the Martells now call themselves Princes. Dorne was the only kingdom in Westeros to be ruled independently from the Targaryens, and did so for 150 years.
After repeated attempts at conquest failed, King Daeron II brought Dorne into the fold by peaceable means, marrying the Prince of Sunspear’s sister and giving his own sister to be the wife of the Prince. Their motto is, “Unbowed, Unbent, Unbroken.”
The current lord of the house is Prince Doran Martell, whose sister Princess Elia was killed in the Sack of King’s Landing and whose uncle Prince Lewyn of the Kingsguard died fighting at the Trident. He has one brother, the notorious and infamous Prince Oberyn Martell, who is called the Red Viper after an incident in his youth when old Lord Yronwood died after duelling with him over Lord Yronwood’s mistress, sparking accusations of the use of a poisoned blade. Wed to the Princess Mellario of the Free City of Norvos, Prince Doran has three children: Princess Arianne is his eldest child and his heir. Before Prince Doran, his mother was Princess of Dorne. She was a close friend to Lady Joanna Lannister, and indeed had tried to marry one of her children to one of Lord Tywin’s twins. He rebuffed her, and always seemed to hold Princess Elia’s marriage to Rhaegar Targaryen as an insult.
The Martells have made alliance with the Lannisters in return for the betrothal of Prince Trystane to Princess Myrcella, a seat on the small council, some castles on the marches, and the head of Ser Gregor Clegane who raped and killed their sister Princess Elia. Prince Oberyn came to claim the seat and press for Ser Gregor’s head. When it was clear that Lord Tywin meant to forego that promise, Prince Oberyn convinced Tyrion Lannister—then being tried for the murder of King Joffrey—to make him his champion.
The Red Viper very nearly won but despite the terrible wounds and the poison introduced with them on Ser Gregor’s body, the Mountain was able to kill the prince. Ser Gregor lies on the brink of death from the effects of the poison.
Dorne’s anger at the Red Viper’s death leads Doran Martell to arrest the Sand Snakes, Oberyn’s daughters. His own daughter Arianne, however, seduces Ser Arys Oakheart of the Kingsguard and convinces him that they can crown Myrcella queen of the Seven Kingdoms. This plot is discovered and Ser Arys is killed, while Ser Gerold Dayne—another member of the conspiracy—nearly kills Myrcella before fleeing. Arianne is imprisoned and is finally brought before her father, who reveals that she had been secretly betrothed to Viserys Targaryen and now that Viserys is dead, her brother Quentyn is traveling east to try and wed Daenerys Targaryen and bring her to Dorne so that the Martells can have vengeance and justice. Arianne proceeds to work with her father to try and win over the Sand Snakes to her father’s plans.
Quentyn Martell eventually finds his way to Meereen, only to find Daenerys on the verge of marrying Hizdahr zo Loraq. Ashamed and unwilling to return to Dorne a failure, he and his companions enlist the Windblown, a sellsword company, to try and steal one of Dany’s dragons after she has flown away on Drogon. Quentyn is horribly burned when his plan fails and the two remaining dragons escape to wreak havoc over Meereen, and dies a slow, lingering death.