Its capital city was called Shumballa (also known as Meroę), the largest in the Black Kingdoms. It was based on pre-Stygian ruins, and its ancient stone walls were frequently patched with log palisades where the walls had collapsed.
Kush gave its name to the whole southern part of the world-continent. Barachan pirates were the first northerners to raid and trade with Kush. Later, Argos and Zingara had a thriving traffic in gold, ivory silver, copra, pearls, and slaves. Kush imported beads, silks, sugar, and brass-hilted swords.
The kingdom was ruled by a brown-skinned, part-Stygian race which despised the black lower classes.
References: Hyborian Age I, Letter to p. Schuyler Miller from R.E.H., Queen of the Black Coast, Castle of Terror, Snout in the Dark, Drums of Tombalku.