Once upon a time, there was a little planet called Azeroth. A shining jewel of the universe, this little planet was chosen by the Titans, blessed by their presence and organized into a perfect representation of order and beauty. But that order and perfection wasn't to last. At some undefined point in the little planet's future, malevolent proponents of chaos, creatures simply called Old Gods, visited Azeroth's surface and quickly decided to ruin the harmonic vision of the Titans with their own brutal, corrupt, and chaotic one.
The Titans realized something had happened and returned to find the world they had so carefully balanced in a state of utter chaos. They immediately launched an assault on the Old Gods, but they discovered something strange. The Old Gods had fully integrated themselves with the matrix of the little planet, placing a strange malaise on the inhabitants. If the Old Gods died, so too would Azeroth -- and so the Titans imprisoned the Old Gods deep beneath the earth where they could do no further damage. They set to work repairing the planet, leaving various safeguards behind to watch over the world. Satisfied, they left -- and they haven't been seen on Azeroth since.
Today's Know Your Lore is a Tinfoil Hat edition, meaning the following is a look into what has gone before with pure speculation on why it happened. The events presented are events that happened in Azeroth's history, but the conclusions are merely theories and shouldn't be taken as fact.