The largest tribe of Animal Nomads, the Impala Nation have the largest number of Orlanth AND Yelmalio cultists of any tribe in Prax. Although Eiritha Impala is the biggest cult of the Impala Nation, Orlanth, Waha, and Yelmalio are all tied for second place.
Despite their shared gods, the Impala nation are not particularly friendly towards either Sartarites or Sun Domers. They are notorious as master skirmishers, and are famed for their skill at “counting coup”.
The Impala were exiled to the Genert Wastes after the First Battle of Moonbroth, but have returned with the White Bull and Jaldon Goldentooth. Despite their shared exile, the Impala have a strong rivalry with the Bison Nation, as both tribe feels that they were betrayed by the other at Moonbroth.
The Impala Nation worship the same entity – Yelmalio – that same Light God who persevered through the Darkness and did not retreat from the world. I’m pretty sure the mundane cult as practiced among the Impala do not bother the fight with Pike or Long Spear, but focus on Bow. But nonetheless, the roughly 9000 Yelmalio cultists among the Impala Nation would recognize their god as the same worshiped at the Sun Dome Temples.
I suspect the cult was introduced to them in the Second Age and for whatever reason the cult appealed to the Impala people. As did Orlanth (likely introduced in the First Age).
One way of looking at it is that the Impala main deities are the Mother of Impalas, her son the Butcher, the Wind, the Light, and the Ancestors.
I regularly refer to Orlanth as “the Storm King” or Ernalda as the “Earth Mother” and so on in games. I’ve long noticed that there is a tendency to fixate on the Gloranthan name more than the divine archetype. A Glorantha sees a Pelorian worshiping what they refer to as the Storm King and a Dragon Pass resident worshiping what they refer to as the Storm King, and they’d likely hold that both are worshiping “Orlanth”. For the Impala, Orlanth is their Wind God and they love him, but they care little about his Rainbringing or tribal kingship aspects.
Same thing with the Little Sun. Loads of folk worship the Light in the Darkness. Call it Lightfore, the Little Sun, the Sky Dome, the Light of the Frontier, whatever. Pretty much everyone now agrees that is the god Yelmalio.
Why does the Impala Nation dislike Sartarites and Sun Domers despite sharing deities? At the root of it, they are nomads, the Sartarites and Sun Domers are agriculturalists.