From A Wiki of Ice and Fire
The Dornishmen, are the natives of Dorne in the southernmost part of Westeros. They have a reputation for hot-bloodedness and sexual licentiousness. They are viewed with some mistrust and rivalry by the people of the Dornish Marches in the neighboring Stormlands. Dornish bastards are given the surname Sand.
Dornish culture has Andal origins, but is mostly influenced by the mass immigration of the Rhoynish people who settled in Dorne during the Rhoynar Invasion. Their influence can be observed in many Dornish customs, like equal rights of women in inheritance law, the status of mistresses/paramours, and their general sexual licentiousness compared to the rest of the Seven Kingdoms.
Dornish lords wear silk and satin robes with jeweled belts and flowing sleeves and favor light armor that is heavily enameled and inlaid with burnished copper, shining silver, and/or soft red gold. 
The Rhoynar were a slender people with smooth olive skin, black hair and dark eyes. Their impact on the Dornish gene pool is strongest along the coast, and grows faint farther inland. Dornishmen with more Andal and First Men blood are larger and fairer than those with more Rhoynish.
- Salty Dornishmen live along the coasts, mainly along the Broken Arm region, where the Red Mountains stretch out into the Sea of Dorne. These Dornishmen are lithe and dark, with smooth olive skin and long black hair. They are fishermen and sailors, hard men who sail the ships of the Dornish fleet.
- Sandy Dornishmen live in the deserts and the long river valleys, faces burned brown by the hot Dornish sun, they are even darker than the salty Dornishmen.
- Stony Dornishmen live in the passes and heights of the Red Mountains. They have the most Andal and First Men blood and mostly resemble the other people of the Seven Kingdoms in look, customs and traditions. They are brown-haired or blond with faces that are freckled or burned by the sun.
Dornishmen prefer round metal shields, spears, short throwing spears or double-curved bows. The Dornishmen are famous for their sand steed-riding light cavalry, and use their double-curved bows skillfully from horseback. Because of the heat, they wear lighter armor than in the rest of the Seven Kingdoms made of metal disks, sometimes decorated with copper, sewn in the manner of scales on the leather. To allow themselves to fight in the burning sun of Dorne, they wear brightly colored flowing robes covering the metal parts of their armor.
Dorne is the least populous of the Seven Kingdoms. As such, it seems to favor different tactics than the rest of the realm, generally avoiding pitched battles and depending on the speed of their lightly armored men and their swift horses, which are more suited to their smaller numbers and allow them to take advantage of the harsh conditions of Dorne. Indeed, the heat and scarcity of water points make the movement and supply of a very large army very difficult. These techniques have proven effective in war against the dragons of House Targaryen and later against King Daeron during the Conquest of Dorne and though their wars against the Reach and Stormlands for a thousand years.
Martin has acknowledged that Spake Martin, 29 February, 2000 historical influences for Dorne include Wales, Spain and to a much lesser extent, Palestine.