The earliest days of Azeroth's recorded history of wars and conflicts detail the events of the War of the Ancients, which culminated in the destruction of the Well of Eternity and the Sundering of the great continent of Kalimdor. While we have vague remnants of history before that time -- wars between troll empires and aqir, the Titanic creation of our world; it is becoming increasingly clear that our scope of knowledge of these early days of Azeroth is quite small.
Pandaria was once part of the main Kalimdor continent before it vanished into the mists, forgotten. But even before the Sundering, Pandaria had a vast, rich history that was far more complex than the snippets of tales and legends from troll or tauren. And while we don't know if the pandaren are native to Azeroth, or Titan creation like the dwarves and gnomes, one thing is imminently clear -- the pandaren are a far more advanced civilization than any other native Azerothian race.