Dangwar

Dangwar is the second planet in the Jappa system in the spinward trailing edge of the Orion arm. Its system contains a total of five rocky worlds, four icy planets, and two Jovian gas giants. Dangwar is the only one that evolved indigenous life.
A large oceanic planet, it is the homeworld of the xhellan, a species of spacefaring reptilian aliens. Nearly twice the size of Earth, Dangwar is highly amenable to life and boasts a rich marine ecology and a surface nearly entirely covered in ocean. The planet is nearly seven times Earth's mass, with its composition being 45% iron, 25% oxygen, 14% magnesium, 13% silicon, and the rest being other metals and trace elements. The planet is layered with a silicate and oxide crust over a mantle rich in silicates and magnesium, all surrounding a large liquid outer and solid inner core of mostly iron. It has relatively high gravity, almost twice that of Earth, but life has adapted to such an environment. Its atmosphere is broadly Earth-like, with 78.8% nitrogen, 21.2% oxygen, and traces of other gases; this dense atmosphere insulated the surface against radiation and solar effects to make conditions highly amenable to complex life. It has no current natural satellites, but it does possess a planetary debris ring, thought to be the result of the collision of two small moons half a billion years ago. The tidal effects partially account for its stormy seas.
Its native sentients, the xhellan, evolved from marine life that was forced onto land during a period of high marine volcanism that saw a mass extinction around 200 million years ago. The xhellan developed agriculture around 8000 BCE and industry in the late 21st century; for over two centuries, the industrialized nations in the north waged war on each other and colonized the rest of the planet's islands. After a long cold war between nuclear-armed states, the xhellan developed peaceful space travel and gradually colonized its nearby worlds and a handful of star systems. They encountered humanity in the 28th century, and became client race and protectorate of the Orion Empire.