The 12th century is 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 from Saladin. (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")
|11th century||Timeline||13th century|