Sigma Draconis III was the third planet in the Sigma Draconis planetary system. This moonless inhabited planet, classified as M-class, had an oxygen-nitrogen atmosphere. The planet was larger and more heavily populated than Sigma Draconis IV. By 2268, the planet's inhabitants had a pre-spaceflight culture with an industrial scale rating of B, which was equivalent to Earth in 1485, and a technological rating of 3. (TOS: "Spock's Brain")
Sigma Draconis system
Sigma Draconis III
According to the Star Trek: Star Charts (pgs. 19, 44), Sigma Draconis III was located in Sector 004 (Sigma Draconis sector), in the Alpha Quadrant.