Great Sundering

The Great Sundering (otherwise known as simply the Sundering, the Shattering, or the Breaking) was a cataclysmic event that book-ended the War of the Ancients approximately 2,000 years ago (Year -1,408 KC). It was caused by the destabilization and implosion of the Well of Eternity, which destroyed eighty percent of ancient Kalimdor's landmass and sent it down to the bottom of the ocean. A massive, ravenous whirlpool called the Maelstrom was all that remained in its place.

Consequences

During the final assault against the forces of queen Azshara, Malfurion Stormrage drew upon the power of the Demon Soul—an artifact used to empower the portal—in order to shatter the connection between Azeroth and the Twisting Nether. However, the unstable portal vortex within the Well of Eternity exploded and radiated massive earth quakes that could be felt across the entirety of the super continent. While the gateway the Burning Legion used to invade the planet was destroyed, the chain of events that ignited resulted in the destruction of eighty percent of the continent.

In the center of the sea that covered the area where the Well of Eternity once stool, the chaotic storm erupted and became an insatiable whirlpool, which would serve as a reminder of the catastrophe that brought about the end of the first Legion invasion.

Azshara was believed to have died in the explosion of the Well of Eternity, but in actuality she and her Highborne had somehow managed to survive and were twisted into the naga. They spent the following centuries recouping and constructing a new capital city at the heart of the Maelstrom.