In Words of Radiance, the Lopen's narration claims that it's just chance that the shattered plains outpost of of "little herdez" is in Sabariel's camp.
But I don't think it is chance. I think the fact that a large majority of the Herdazians chose to live in the war camp of one alethi high prince that is inn common law marriage to a Herdazians dark eyes is a strategic choice.
Sabarial's camp is not a great place if you want to die to avenge an Alethi king, but it's a great place to make money as a merchant or farmer but don't have a store or land, and it's a great place if you want to sell Sabariel's mistress all the comfort of home.
Those rich merchants selling luxuries, will are more likely to employ other Herdazians for any job from trusted clerk to chamber pot scrubber. Those employees want simple food from home, childcare that speaks thier native language, and probably thier own Ardents. As more and more Herdazians come, they settle with kin. And the small community would have grown fast over the corse of five years.
I'm sure there was still discrimination and harassment for Herdazians in sabarial's camp from Alethi. But there were probably also a lot more people in Sabarial's camp willing to pay a Herdazian a fair days wage, or sell or buy Herdazians food and ingredients, or even learn to speek a bit of of the Herdazian language.
If every options sucks, people will chose the option that sucks a little less, and Sabarial's camp sucked less.
