Dorne is the most isolated of the Seven Kingdoms, something that is a great source of pride to the proud region. This is also true of their population: Dorne hosts a great level of diversity that is not seen elsewhere in Westeros, partly due to its semi-autonomous privilege, and partly due to discrimination seen against its people in northern kingdoms.
The climate of Dorne is unique due to its deserts and dry mountains not seen elsewhere on the continent. There are several major river valleys that cut into the deserts and provide lush areas for farming, something that spread further as canals and irrigation methods were enhanced in the region.
There are four major ethnic groups in Dorne:
Stony Dornish: these are bronze skinned Dornishmen that mostly hail from the Red Mountains and can trace their ancestry back to the First Men. A closely guarded secret, but several mountain houses continued to upkeep Weirwood trees within their keeps to show pride to their ancestry. This is a common theme among the different Dornish races. However, due to their proximity with the Reach and Stormlands, there are some houses that have heirs of lighter skin and hair colors than most common Stony Dornish.
Salty Dornish: these are the Dornish that live along the coastline and are mostly a mix of Sandy Dornish and Orphans of the Greenblood. Thus, it is common to see many shades of brown skin and hazel or brown eyes. However, this is also continuing to grow with new populations from Essos and beyond. Dornish ships that come upon slaver's ships at sea bring the slaves they retrieve back to Dorne and freedom in Westeros, which has led to an influx of New Dornish from the Summer Isles, Naath, Lhazar, and even the Jade Sea. In port cities like Godsgrace and Plankytown on the Greenblood, Starfall at the end of the Tourentine, and Wyl on the Wyl, small sections of the towns have become homages to the homelands of these refugees.
Sandy Dornish: these are the darkest skinned Dornishmen. Their ebony skin protects them against the harsh glare of the sun against the sands. These are the hardiest of the Dornish and include some nomadic groups that move with the change in rainy and dry seasons. Houses and clans can be told apart by the styles of their curly and wavy hair. Certain braids are only used by certain houses. The Sandy Dornish are also notable for their ceramics and glass blowing.
Orphans of the Greenblood: this smallest group are the lightest skinned of the Dornishmen, tracing their ancestry directly back to the Rhoynish refugees that fled Valyrian rule in Essos. They continue their riverfaring way of life on the Greenblood river in Southern Dorne and worship the Mother Rhoyne. Most have olive skin and dark purple eyes.
The Martells are the royal family of Dorne. Descended from Andals like the Salty Dornish were, they merged with the Rhoynish under the marriage of Princess Nymeria. This leads to animosity from the Sandy and Stony Dornish and the internal politics of the region, with Stony like the Daynes always challenging power. However all agree: Dorne comes first.
Doran is the eldest prince. His dark hair and eyes are common among the Dornish, although his skin is paler than most due to the past decade spent indoors as a result of his loss of mobility from gout. Elia was the second child, with similar dark, wavy hair but more angular features than her brother. Oberyn is the youngest of the three, with similar hair but a violet ring to his dark eyes. His lithe figure is much like that of other Salty Dornishmen, however his bronzed skin is covered with inked tattoos collected in his travels throughout Essos and beyond.
Arianne is the heir to Dorne. She is the eldest child of Doran and his estranged wife from Norvos, one of the Free Cities in inland Essos and rich with Andal ancestry. She has thick, curly dark hair and dark eyes, however her petite frame is reminiscent of her mother. Quentyn and Trystane are her younger brothers, and both draw their figure from their father's Salty Dornish roots with their coloration from their mother's Andal ancestry (tall, lithe with strong jawlines paired with straight hair and brown eyes).
The eight daughters of Oberyn are known as the Sand Snakes. The eldest four are from varying regions and thus wildly differ in appearance. Obara was born to a brothel woman in Oldtown, although her thick brown hair and hazel eyes suggest Ironborn ancestry. Nymeria's mother was a Volantene noblewoman, and her long, straight hair and violet eyes are a common feature of the "last children of Valyria"; her black hair and olive skin are from her father. Tyene's mother was a septa in the Reach, but probably from the Westerlands originally due to Tyene's golden hair and aqua eyes. She is the fairest featured of the group. Sarella was born to a captain from the Summer Isles, yet her kinky black hair and dark skin has her mistaken to be of the Sandy Dornish. Her hair is usually kept in tight braids, something she keeps when as Alleras in the Citadel.
The younger four Sand Snakes have the same biological mother: Ellaria Sand, a Sandy Dornish bastard of the Hellholt. Elia is the eldest and said to be a miniature Oberyn, with wavy black hair and angular facial structures. Obella's dark eyes flash violet in the light, and she has kinky black hair and dark skin like her mother. Dorea and Loreza are the youngest and mistaken often as twins with their bronze skin and tight curly hair. The one difference is her eyes, with Dorea's matching their father's and Loreza's matching their mother's.
There are few surviving records describing Rhaenys and Aegon Targaryen, children of Elia Martell and Rhaegar Targaryen. Most remember Rhaenys to have Sandy Dornish features set off with the bright violet eyes of her Targaryen father, while young Aegon was known to have silver hair.