Here’s an early draft of one of the maps that will appear in some form in the Guide to Glorantha, an overview of Fronela population and cultural groups.
What I found particularly interesting here was how widespread the Orlanthi culture and religion is in late Third Age Fronela.
Clearly Fronela (outside of Loskalm and Sog) is significantly less Malkioni than is commonly assumed. Lightbringer cults can be found in Oranor just outside of Fronela, and a large minority of the population of Junora worship gods including the Lightbringers. Only a small (but very powerful) minority of the kingdom of the Jonatings are Malkioni; the rest worship gods and goddesses likely similar to their kin on the other side of the Rockwoods.
Of course this makes perfect sense. Theyalan lightbringers came to Fronela after the Battle of Eleven Beasts in 300 S.T., and after returning from his Second Lightbringers Quest, Harmast Barefoot stopped a war between the Orlanthi of Ralios and the Malkioni and animist Fronelans when he returned the dead Fronelan hero Talor the Laughing Warrior from the underworld. Both joined to attack Kartolin Pass and Dorastor.
A Seshnegi and Jrusteli army conquered Akem in the 8th Century and the Middle Sea Empire dominated the Janube river for the next two centuries. The highlands of southern Fronela were largely unmolested by either great Second Age empire, in contrast to the Janube river valley and the ancient lands of Akem.
Another interesting bit is how many solar cultists are in the Janube valley. The area controlled by the city of Southpoint is 80k. Not shown is the Sun Dome Temple which presumably has some association with the Carmanian empire (presumably this was a frontier garrison of the Carmanian empire). Nearly a quarter of a million people make up the Lunar Arrolian confederation (see Tales Number 20).
Of course the kingdom of Loskalm is the 800 pound gorilla in Fronela, straddling the Ozur Bay. Sog is not part of the kingdom, and is likely one of the most cosmopolitan areas of Glorantha with its 600k residents including representatives of just about every imaginable population group.