The Traders of Roshal, also known as the Traders, are the slave traders located in Roshal.
The Traders of Roshal are a nation, a power unto themselves. They are similar to Wistram Academy, as Roshal can just be as dangerous in its own way. They have their own army, and more money and wealth than most nations could dream of. They have countless magical artifacts hoarded away, and they would defend their possessions to the death.
The Traders have ways of compelling obedience, of defending themselves. Even Named Adventurers must tread carefully because those who break Roshal’s rules will die, no matter where they are. There are assassins and groups of trained killers that have slain monarchs who go against Roshal. And the Traders have countless thousands of years of knowledge. They know secrets of classes and leveling that even Kings and Rulers don't know, such as the Horror Ranks and Aspects.
As noted by Trey, most of the slave traders of Roshal consist of String People.