Aeroden was the previous god of the area (Cheliax). He died in 4606 of natural causes. Westcrown was his seat of power.
When Aeroden died, the House of Thrune took over. The House of Thrune moved the capital of Cheliax out of Westcrown. They installed Asmodeus as the local god and installed Arvanxi as the governor.
Westcrown consists of 3 main areas: Island (affluent), North (abandoned), South (cool). Slavery is legal and mostly Halflings are slaves. There is lots of vice in Westcrown. The population is around 110,000. There are two orders of law in Westcrown: Hell Knights, who serve Cheliax as a whole and Dotari, who are the local “cops”.