Berez had once been a small riverside village of swamp-folk in the Zarovich Valley, set along the Luna River. It held little strategic value, but its people maintained old customs tied to the swamps and the nearby fane across the river. During the early von Zarovich conquests, settlers from the Village of Barovia displaced many of the local swamp-folk, and the town became an uneasy mix of traditions. By the year 400, Berez was ruled by the burgomaster Zann Ulrich, whose hoarded wealth contrasted with the village’s slow decay.
Strahd von Zarovich, traveling under the name "Vasili von Holtz", came often to Berez to purchase Ulrich's family Spellbooks. During these visits, he discovered Marina Ulrich, the burgomaster’s adopted daughter, and recognized her as an incarnation of Tatyana Federovna. He began to court her in secret, and eventually moved to seduce the obsession of his former life. When Zann learned of this, he staked Marina through the heart before Strahd could claim her, and buried her in the village graveyard. He then confronted Strahd directly, attempting to destroy him as well. Strahd easily felled the burgomaster and, in his rage over Marina’s death, turned his wrath upon the village itself.
The Luna River swelled beyond its banks at Strahd’s command; in an attempt to keep neutrality, the Lady of the Swamp, who held power over Barovia's waters, did not contest him. The swell tore through Berez, collapsing homes, drowning its people, and erasing the village in a single ruinous surge. Many swamp-folk died in the flood, including followers of the Lady; feeling horror at her inaction, she Cursed Strahd for the slaughter, an act that would ultimately result in her hunt and the Desecration Of The Swamp Fane.
In the aftermath, Berez was abandoned. Strahd did not kill Zann outright, but carried him away to years of torment before remaking him as a Vampire Spawn. The Luna River slowed and spread into bog and marsh, choking the old roads with reeds, mud, and stagnant pools. What remained became a place of witches, covens, and Scarecrows under Baba Lysaga's loose dominion, while the souls tied to Berez lingered, trapped in repetition like so many others in Barovia.