A few caravans...that we know of. Nomadic peoples often have surprisingly more of them than anyone expects out and about, until a reason for them to stop being nomadic comes up. And if they're passed all the remaining treasures and knowledge of ancient Sarnor, I think we could be looking at a very relevant ally in the local geopolitical sphere. It also means that we don't have to move people in wholesale when it comes to absorbing the area, we'll already have them on good terms - probably a client state - and it'll just be a matter of formalising that relationship.
That's worth the trade.