Brachiosumeria is a collection of city states each led by its own priest king, each of which venerates a specific patron deity. Temples within the city still offer charms and prayers for other deities (though a specific deity’s services may be suspended if they’re patron of a city the temple’s city is at war with), but one god in particular is considered higher than the rest. Thus, a citizen of the fire god’s city can still get blessings from the god of night, or the god of war, or the god of the sun, but they’ll do it by going to a temple run by fire priests where the fire god is venerated above all others, and will probably be required to make sacrifices to the fire god in equal amount to whatever god they actually want to solve their specific problem.
The priest king of a city claims his position through divine right, often claiming to be descended from the city’s patron god, and is initiated into all the greatest secrets of the priesthood. The king’s high priests are likewise initiated into all or most of the secrets, and rank in government remains tied to knowledge of mystical/religious secrets all the way down to magistrates of hinterland villages being the local priests of that village and town guards being supplied with charms (sometimes purely symbolic) of the god whom they ultimately serve. Government scribes and captains of the army, officials whose actual skills are completely unrelated to religion, are still required to know enough prayer and ritual to pass as an acolyte of the faith and to wear the holy symbols of the patron god.
Differences between one Brachiosumerian city and another are not as significant as you might think, given this. The fire god’s city has giant bonfires on festival nights, and the night god has…also lots of giant bonfires, so that festival goers can see what they’re doing in the middle of the night. The sun god’s festivals take place during the day (and at different times of year), but also include lots of drinking and dancing and music, just like everyone else’s festival. Every god considers it their divine mandate to rule over all others and will raid other cities to do so, and festivals are more extravagent when the city’s had a good raiding year and more subdued or even cancelled altogether when it hasn’t. The priesthoods of the god of fire and the goddess of blood have very different cultures from those of the god of the sun and the god of law, but for the citizens of a city they’re pretty much just tribal rallying points.
The Brachiosumerian militaries are small, professional armies comprised primarily of heavy infantry, backed up by levies equipped with a bow. Although relatively rare, the brachiosaur superheavies of the Brachiosumerian city-states tend to dominate their military formations simply due to their massive size. Each city can usually field only a half-dozen or so of these massive war beasts (compared to hundreds of professional infantry and thousands of levies), and it is more common for them to be boarded and captured rather than slain, both because of how valuable they are and because of how impossibly durable they are.
Working for Brachiosumeria
Each individual Brachiosumerian city-state controls the resources of just one city, and raiding is typically preferred to trade as a means of acquiring resources that the city lacks. Raiding is not a very reliable or efficient means of acquiring resources, which means that merchant caravans are very valuable, even as they are at greater risk in a wartorn land full of bandits, deserters, and enemy armies. Brachiosumerian city-states are also more than willing to hire foreign mercenaries for their wars, and because society is more about tribal allegiance to a specific god than following any specific code of laws, any such foreign mercenaries willing to kiss the ring are effectively citizens of the Brachiosumerian city-state even if they don’t actually live there.