I see your point, however the RP is set 200 years after the actual GOT series so that would allow for about 7-8 generations to pass. During that time it could be possible for some of the Dothraki that came with Daeny to intermarry with non Dothraki, integrate with Westeros culture, and while they still won't hold power due to their ethnic background they could find work with powerful people. Positions such as handmaidens, bodyguards, etc. What I was hoping to do was have a Dothraki be a hired mercenary for any of the houses and basically be like Tyrion's sellsword Bronn.