Azkaban was established after the International Statute of Secrecy came into effect.
People realized that small wizarding prisons were impractical, because prisoners trying to escape often made noises, smells, and flashes of light that attracted Muggle attention.
After many twists and turns, in 1718, the North Sea island inhabited by Dementors was selected as a prison by the Minister for Magic at the time, Damocles Rowle.
Thus, Azkaban was born. The criminals of the British Wizarding World had a home, and Hogwarts gained a fifth house, centuries after its four founders had died.
Quirrell had never been here, and neither had Voldemort, but now that the "Dementor Training Camp Initiative" had been approved, they had the chance.
It hadn't been easy to make this happen. First, there was the question of how to use Dementors safely. Several professors had studied and discussed it together before finally finding a solution.
Then there was the question of passing the Board of Governors' review. These wealthy donors had no real power at the school, but sending such dangerous creatures there gave them ample reason to reject the proposal.
Everyone had assumed Malfoy would be a major obstacle. Perhaps he would use this matter to force Dumbledore to compromise. Unexpectedly, he didn't.
"A wise decision," he said at the Board meeting. "Let those Muggle-born wizards learn that the Wizarding World isn't safe. Perhaps they'll leave as soon as possible."
Pure-blood rhetoric was hateful, but the governors were all Pure-bloods, and few objected to his remarks. When a group of Pure-bloods got together, they couldn't even be bothered to put on an act.
Dumbledore was, of course, unhappy with what he'd said, but to get the proposal through, he didn't go looking for trouble.
And so, a group of Pure-blood governors, hoping to frighten the