The 12th century was defined by the calendar of Earth as occurring from the year 1101 through the year 1200.
- The Second and Third Crusades are fought on Earth (1147-48 and 1189-92). In the latter war, King Richard the Lionheart fails to take Jerusalem. (TOS: "The Squire of Gothos"; DS9: "Q-Less"; VOY: "The Killing Game")
- The spheres are constructed by the Sphere-Builders. (ENT: "Anomaly")
- Vissians were said (in 2153) to have developed warp capability "nearly a thousand years ago", placing it at some point after 1153. (ENT: "Cogenitor")
- According to the Star Trek: Star Charts (p. 52) and the Stellar Cartography: The Starfleet Reference Library ("Federation Historical Highlights, 2161-2385") , Andoria became warp-capable in 1154.
- According to the Star Trek Encyclopedia (3rd ed., p. l71), Genghis Khan was born in c. 1162.
- Cambridge University is founded in Great Britain. (Star Trek Encyclopedia (4th ed., vol. 1, p. 114))
|11th century||Timeline||13th century|