Complex sentence: Tanzhou or Tan Prefecture (潭州) was a "zhou" (prefecture) in imperial China centering around modern Changsha, Hunan, China that existed (intermittently) from 589 to 1372.
Split into simpler sentences: Tanzhou or Tan Prefecture (潭州) was a "zhou" (prefecture) in imperial China centering around modern Changsha, Hunan, China. It existed (intermittently) from 589 to 1372.