Rumtara Kingdom was decently far away from the Brimgan Empire, but throughout history, migrants had braved through the treacherous regions to arrive at the Brimgan Empire.
It was because of the consistency at which Rumtara Kingdom remained a fucked-up Kingdom with piss-poor leadership. And every time they were raided by a Pranic Beast race, resulting in lots of Free Human deaths, a large number of people migrated from there.
This had happened hundreds of times to the extent the migrants managed to forge a path of escape that allowed them to travel from the Rumtara Kingdom to the Brimgan Empire with relative safety and a conservative number of deaths.