Burned Men derive their name from their coming-of-age ceremony, in which they mutilate themselves by burning off a body part of their choosing, usually a finger or nipple. The more important the body part burned, the more prestige the warrior gains. They are feared by the other clans because of this practice. Red hands are war chiefs of the Burned Men.
The Burned Men are seemingly an offshoot of the Painted Dogs that branched off in the years after the Dance of the Dragons. They were said to have worshiped a fire-witch, sending their boys to bring her gifts and risk the flames of her dragon to prove their manhood. Gyldayn suggests they were Nettles and Sheepstealer.
A Game of Thrones
A Clash of Kings
A Storm of Swords
After the Battle of the Blackwater, Timett and his clansmen take their plunder and return to the Mountains of the Moon. A village elder tells Sandor Clegane that the Burned Men under Timett have become fearless.