I've been thinking for a little bit of how to make my country a stew of different irl native cultures while still being a feasibly united country. I was thinking that the villages along the river have a more Polynesian/Maori style culture centered around fishing and a warrior tradition. The western border and northwest could be a Sub-Saharan African style culture centered around hunting game and foraging in the jungle/forest. The northeast could have a Nordic culture inspired by the neighboring Til-Gur. The indentured servitude of Til-Gur could have also bolstered their pro-slavery views. They are focused on mining. The center would be plains and grasslands inspired by Midwestern Native Americans with slight Adduni influence. They could be mostly farming and livestock with homesteads hunting herds of buffalo and similar animals.