Proxima Centauri

Background
Proxima Centauri, formerly known as Alpha Centauri C, is a star system roughly 4 light years from Earth, and containing three planets. The system is home to the Kashni people, who originated from Proxima Centauri-b. Proxima Centauri was included in Alpha Centauri until the discovery of the Kashni Empire and their latent hostility in 2217. The Kashni Empire allegedly attempted to construct a 'Dyson-sphere' around Toliman, the smaller of the two stars of Alpha Centauri, in 2224, beginning the war between them and the RSC.

Planets
A total of three planets orbit the star. Many Earth citizens refer to the planets as -b, -c, and -d, but are known locally by the Kashni as Senna Hanna (meaning 'new home'), Harai (named for its discoverer), and Kaui (named for its discoverer). Senna Hanna is the home planet to the Kashni following their migration from TRAPPIST-1. It is unknown when the other planets were terraformed and colonized. Harai is a gas giant, roughly between the sizes of Neptune and Saturn. The Kashni have constructed airborne cities in the dense clouds in its atmosphere. Kaui is a dwarf gas giant, roughly the size of Venus, and boasts similar air cities. '-a' is a small dwarf planet about 2/3 the size of Pluto, and only holds a few colonies that serve as solar stations for energy.

History
The system was chosen by the Kashni following the collapse of the Ha'Ruu and the mass migration from the TRAPPIST-1 system. -b or Senna Hanna was a very similar planet (except for its size) to their original home planet of TRAPPIST-1-d. Being silicon-based lifeforms, Kashni can survive the extreme cold temperatures on '-d' or Kaui with little issue.