Battledepths?

How to make dwarves in battledepths appear? I enter it, go to the dwarves place and it's empty!

I think they appear there once you've done all 3 Asura, Norn and Vanguard quests on your character. The storyline then dictates that you do Destruction's Depths, at which point you'll get the Dwarves in Battledepths.

If I'm wrong, someone correct me, please.

As taken from the Unofficial Wiki:

- Note: The Dwarves will appear only after you have completed the primary quest Northern Allies.

Following through the Northern Allies quest chain the one cinematic shows a raven being sent with a message to the dwarves, asking they come up to the north...hence why they're not there beforehand