12th century
The 12th century was defined by the calendar of Earth as occurring from the year 1101 through the year 1200.

Events
 The spheres are constructed by the Sphere-Builders. ()
 Vissians were said (in 2153) to have developed warp capability "nearly a thousand years ago", placing it at some point after 1153. ()
 The events surrounding Robin Hood take place in England. ()

 Trill Commissioner Vos noted that in the two-thousand years prior to 3189 (since approximately 1189), there had never been a successful instance of a symbiont joining with a non-Trill species. ()

Appendices

Background information 
 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.
 Genghis Khan is born in c. 1162. ()
 Cambridge University is founded in Great Britain. ()
 The Second and Third Crusades were fought on Earth during this century.

External links 
 
 

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