There are some 2.4 MILLION Orlanthi in Fronela, far more than in Dragon Pass and Peloria.
The Lightbringers came to Fronela in the First Age, reaching what is now Charg by 238 ST and Oranor by 317 ST. The cult established strongholds on both sides of the Nidan Mountains, as the Lightbringers also came to Vesmonstran even before that time (around 204 ST). The Lightbringers have been the dominant cults in that area for more than 13 centuries.
With 1.6 million people, the Kingdom of Jonatela is the largest Orlanthi confederation in Fronela, and second only to Esrolia in Glorantha. It is ruled by a superficially-Malkionized king (as in he claims all the rights of a ruling Talar while still offering sacrifices to the Lightbringers and other deities) descended from Jonat Big Bear The king directly rules Syranor and is allied with several lesser tribal confederations.
During the Ban, these Orlanthi regions were largely isolated from each other for more than a century, allowing them to develop their own institutions and blend of cults and philosophies.
Prior to the Ban, Charg included the Baloris tribes and the Bull Lords of Vangstal, the so-called Urox-land. These tribes placed the Bull Shahs on the throne of Carmania and were their most ferocious supporters. After the defeat of the Blood Kings, the lands west of the Esel River remained independent of the West Reaches and never submitted to the Red Emperor.
Of the different Orlanthi kingdoms in Fronela, which would be the most interesting to set a campaign in, and why? Really depends on what you want to do. Jonatela is a rough-and-tumble “barbarian” kingdom – think medieval Russia, Merovingian France, etc. Dangerous politics, with sorcerers and shamans, but also traditional Orlanthi cults and tribes.
Now if you look at those dates on the maps, what is interesting is how recently Jonatela appeared. The kingdom has risen out of nowhere in the last ten years.