Valyrians are pale white with silver hair and purple/blue/green eyes. Not just white, pale white. Not just Targaryens, all Valyrians.

Dark-skinned people come from The Summer Isles and Naath, not Essos.

These two were boldly mentioned in books and the show but they ruined the show with making lord Velaryon and his descendents black. No one would complain if characters like blood and cheese and Marston Waters were black. However a black velaryon is silly.

A world of Ice and Fire is based on medieval Europe, specifically Westeros. The whole point to the alieness and strangeness to the Targaryens is that they are a pale, white haired , purple eyed race from Essos(Asia) that tamed dragons. They are obsessed with keeping their bloodline pure so much that they marry brother to sister. When the 12 year old Velaryon girl says she will give him many pure blooded Targaryen children I nearly spit out my drink. I'm all for racial diversity in casting but this makes no sense. You have two whole other continents and the summer Isles to cast those with a darker skin tone.