Long, long before the rise of human and orc, the world of Azeroth was far different than it appears today. Instead of the multitude of continents we know of, there was simply one: Kalimdor. It was essentially Azeroth's version of Pangaea -- a supercontinent that covered the world. Places that we travel to today, Northrend, the Eastern Kingdoms, even the islands off the coasts of the world were all part of the massive continent. This was Azeroth, back in the day -- one world, one continent, and a lot of Old Gods.
Theories seem to be mixed on which came first, the Titans or the Old Gods. The latest theory came from the Tribunal of Ages, which implies that the Titans ordered the world and left, then the Old Gods arrived, and then the Titans returned to deal with the problem. After imprisoning the Old Gods, the Titans created safeguards to protect the world, safeguards that would prevent the rise of the Old Gods -- and in the event that the Old Gods returned, safeguards that would go so far as destroying Azeroth itself. Watchers and Aspects were both created and charged with protecting the fragile world.
And, according to various pieces of history, the Titans created the Well of Eternity.
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 what is to come as a result. These speculations are merely theories and shouldn't be taken as fact or official lore.