Vampire: The Dark Ages
From the White Wolf Wiki, the most complete White Wolf reference
Vampire: The Dark Ages is a historical setting for Vampire: The Masquerade which takes place in the Dark Medieval period — specifically, 1197, a period referred to as the Long Night.
The Dark Ages line both expanded on the history and setting of VTM by adding historical data and filling in gaps, as well as by introducing mechanisms later used in Vampire: The Masquerade Revised Edition. Many of these concepts were later folded back into Dark Ages, revising it as Dark Ages: Vampire, which took place in 1230, during the era of the War of Princes.
