Ru is the capital of Atash, one of the Seven Satrapies.

Before the war, Ru was famous for its castle and Great Pyramid. Despite the destruction of the castle during the war, it is still famous for the Great Pyramid.

During the War Of The Prisms, it was sacked, and its citizens massacred, by General Delmarta, a commander loyal to Dazen Guile, who was thereafter called the Butcher Of Ru. The Satrapah at the time, Naheed, had her unborn child cut out of her and thrown him down the steps of the Castle Of Ru, after which the soldiers cut off her nose, ears, breasts, legs, and arms, then threw her down the steps as well. Delmarta was a young, new general at the time, and Dazen appointed him to his command due to his reputation for being efficient and direct, and directed him to secure Ru. Delmarta, much to Dazen's horror, interpreted that to mean secure it so that there could never be any resistance ever again. Delmarta exterminated all 56 members of the royal family, as well as scores of their retainers, publicly, one at a time, in order of their succession, and burned down their great castle, which had been the pride of Atash. One of the members of the royal family who was killed in the massacre was Meena, favourite little cousin of Samila Sayeh, who was 7. When the citizens of Ru fled in a refugee flotilla, Delmarta sent fire drafters after the flotilla, who sank every ship, none of which had a single drafter or armed man on board. As a result, when Delmarta marched on the city of Idoss, it surrendered immediately.

In retaliation for the horrors visited on Ru, the Atashians burned Garriston, capital of Tyrea and birthplace of Delmarta, to the ground, and barred the gates of the city so that no one could escape. All of Tyrea's drafters, as well as all but 200 of its soldiers, were 100 leagues away from the city at the time.