Sigma Iotia II was an M-class planet, the second in the Sigma Iotia system in or near Federation space. It was home to the Iotians, a race of highly-imitative humanoids.
Beginning in the mid-22nd century, Sigma Iotia II underwent a series of cultural upheavals that began with "contamination" by the Earth vessel Horizon. The Horizon crew left a book behind on the planet, Chicago Mobs of the Twenties, which had great planetwide influence. When the USS Enterprise was sent to investigate the planet a hundred years later, they found that the Iotians had built an entire society based on the mob lifestyle. The planet was eventually made a Federation protectorate, and would send a "cut" of their "action" to the UFP. The Enterprise departed Sigma Iotia II, and it appeared as though the contamination was at an end. However, Enterprise CMO Leonard McCoy accidentally left his communicator behind on the planet, which would trigger another cultural evolution. (TOS: "A Piece of the Action")
Within a generation, the Iotians had built a starbase and many wore clothing similar to Starfleet uniforms of the 2260s. In 2271, they sent a delegation to the Federation Council, and by 2366 Sigma Iotia II had become a Federation member. (The Worlds of the Federation; TOS novel: The Lost Years; SCE novel: Fables of the Prime Directive)
Renova Exler was born on Sigma Iotia II, and grew up in the care of her grandfather. A small-time pickpocket in her youth, she attempted to steal from Starfleet officer, Sayzar Tyrellian. Tyrellian took her under his wing, and ensured her a place at Starfleet Academy. (Star Trek: Outpost)
Alternate continuities[]
Project Potemkin[]
By 2299, Klingons had visited the planet, and the indigenes used prosthetics to make themselves look like Klingons, though they retained the gangster accouterments from when the Enterprise had visited them in 2267. (Project Potemkin: "All in a Day's Work")