Human ethnic groups

[Ianesta]

I'm a little bit confused about some of Avistan's ethnic groups. The Shoanti are, according to Humans of Golarion, present all the way up from Varisia to Land of the Linnorm Kings and along to Numeria, yet there's very little else on that group outside Varisia and a little bit of Belkzen. Brevoy on the other hand has Varisian listed as a major language, yet I've seen little to suggest they're a major ethnic group there.

I have a big interest in ethnic politics in real life so I'm pretty curious about the make-up of Avistan's various regions and their interactions, the migration map in Humans of Golarion was a nice touch I'm just having trouble making sense of a few little bits.

[Simeon]

The Varisians are fairly nomadic and tend to pass through Brevoy on their journeys. However, the Shoanti are fairly scattered and insular. They tend to look down on outsiders for robbing them of their way of life. You can find in-depth info on the human ethnicities here

[Irnk, Dead-Eye's Prodigal]

Varisians are fairly thoroughly documented from the Lost Coast to at least the shores of Lake Encarthan (Ustalav says Hi!)
Shoanti don't really seem to have much in the way of a presence farther East than say midway through the Holds of Belkzen & I don't really recall indications they go much farther North than the Kodar Range (The mountain range between Varisia & points North)