Ulong Lai / Summer's Domain was created by Gurang Zhi / Solane to be one of the four Rune Pillars bordering Plumamentia - specifically, the furthermost South. It embodied, amongst other things, the concepts of creation and of expansion, and was guarded by Ulong Lai / Summer, one of the four Dragon Lords / Laiwang.

At some point during the Second Era, the Azurites murdered Ulong Lai / Summer and destroyed Summer's Domain.