Lh'owon was the homeworld of the S'pht.
In S'pht mythology, Yrro built Lh'owon with the S'pht as his own paradise, but following Pthia's death by the W'rkncacnter, he gave Lh'owon to the S'pht for them to live on.[1]
Originally a marshy planet, a series of inter-S'pht clan wars devastated the planet. The Pfhor's subjugation of the S'pht also involved the use of nuclear weaponry. By the time Durandal discovered Lh'owon in the Boomer, it was mostly desert.[2]
For a thousand years before the events of Marathon 2: Durandal, Lh'owon was an outpost for the Pfhor Empire.[3]