(warning contains light spoilers for the book I’m writing)
Adora is a city state in the world of Aiur. It has a democratic government similar to the Roman republic in our world, but with quite some differences as well.
20 or 30 years before the story starts Adora went through a large revolution. During this time a “coalition” between the priesthood and the poor tried to dramatically improve the lives of the poorest in society. This of course created tension with the wealthy people in society. These tensions eventually escalated into a civil war during which drove the vast majority of the wealthy people out of Adora. Just like many Cubans fled to the US after its socialist revolution, or (to take a example from my neighborhood of the world) like many people fled from Antwerp to Amsterdam when Antwerp was sacked by the Spanish, many Adorans fled to Syinthia. When many of the wealthy people fled Adora, many of the Atheists, and people with small underground religions went with them. They feared religious persecution under the now even more religious government, and the departure of the wealthy created the perfect opportunity to come along.