Some believed that the sand tribe may have been the largest of the tribes, but their nomadic and hostile nature made it impossible to get an accurate count of their number.
The Zesk and Vorox did retain some intelligence. They did not have the same spoken language as Agori, although they could manage a broken version of it. It could be assumed that they had names they called each other in their own language.
The Zesk and Vorox were fairly reclusive to start with, which contributed to their reversion to barbarism. The Sand Tribe had always been nomadic. The Sand Tribe was very populous even before the Shattering.