In Central Genertela, their aren’t a lot of cults that more than 30% a region’s population belongs to. Such a cult strongly defines a given region and would be present nearly everywhere. Here’s a list of a few such cults:
Orlanth – in Sartar, Old Tarsh, and Heortland.
Ernalda – in Sartar, Grazelands, Old Tarsh, Caladraland, Esrolia, and Heortland.
Eirtha – among the Bison, High Llama, Impala, and Rhino Tribes.
Waha – among the Bison, High Llama, Rhino, and Sable Tribes.
Invisible God – in God Forgot only.
Pavis – among the Zebra people only.
Yelorna – among the Unicorn people only.
Seven Mothers – in First Blessed and Silver Shadow.
Aldrya – and brown, green, and yellow elves.
Kyger Litor – Dagori Inkarth, Shadow Plateau, Troll Woods, Elder Wilds, Yolp, and Blue Moon Plateau
Argan Argar – in Shadow Plateau and the Troll Woods
Zong – Elder Wilds only