Kaitain was the Imperial Capital of the Corrino Empire. It had 4 moons.
The planet became the capital when the Imperial Seat was moved from Salusa Secundus—Salusa Secundus having become a wasteland after the intended destruction of House Corrino by House Tantor using atomics. That planet subsequently became the Emperor's prison planet.
When House Atreides wrested the Empire from the Corrinos in 10,193 A.G. the Imperial Capital moved from Kaitain to Arrakis, where it remained on Dune until the death of Leto II approximately 3500 years later. Two years after the ascension of Paul Atreides to the throne, Paul's Jihadi warriors decided to ransack Kaitain, and destroyed many of the magnicficent buildings in the planet's capital, Corrinth City.
After the vandalism and wanton destruction by the Fremen troops, Kaitain never regained even a fraction of its former importance or glory.