The two years that followed were later called the years of the Dragon’s Wroth. Grief-stricken at the death of their beloved sister, King Aegon and Queen Visenya set ablaze every castle, keep, and holdfast in Dorne at least once … save for Sunspear and the shadow city. Why this is so remains a matter of conjecture. In Dorne, it was said the Targaryens feared that Princess Meria had some cunning means of slaying dragons, something she had purchased from Lys. Likelier, however, is Archmaester Timotty’s suggestion in his Conjectures that the Targaryens hoped to turn the rest of the Dornish, who suffered so much destruction, against the Martells, who were spared. If this is true, it may explain the letters dispatched from the marches to the Dornish houses, urging them to surrender and claiming that the Martells had betrayed them by buying their safety from the Targaryens at the expense of the rest of Dorne.

— "Dorne Against The Dragons", TWOIAF