Middle Ages
From Tardis Wiki, the free Doctor Who reference
The Middle Ages were an era in human history following the Dark Ages.
At some point during the Middle Ages, (TWN: Something in the Water) Strepto was stolen by the Daleks. (REF: The Time Traveller's Almanac)
Compared to the 21st century, Britain was on average three degrees colder in the Middle Ages. (K9TV: The Last Oak Tree)