Shamash is Assyria IV, a large rocky planet with 600 million inhabitants.
Physical Geography
Shamash is quite large, with a gravity of about 2.4 times Earth gravity. It has abundant sulfur and an overall reducing chemistry. The atmosphere contains abundant hydrogen sulfide and hydrocarbons. The planet has substantial cloud cover and a surface temperature average of about 150C.
History and Culture
Shamash was uninhabited during the Imperial age, and was first colonized by exiles from Larsa in the Dark Age; it later became a sort of penal colony. (Transport from Larsa to Shamash is relatively favourable energetically.) Inhabitants are concentrated in a few mountaintop colonies where temperatures and pressures are more conducive to Terrestrial life. Some inhabitants live in cloud cities, which are mobile.
Economy
Its gravity well and thick atmosphere make getting to space from Shamash unappealing for bulk transport, and its nearly Earth-sized moon Larsa is self-sufficient in anything Shamash might offer. Its economy is essentially subsistence-based and it is arguably the poorest of the Allied Worlds, though it is certainly liveable.