Balrog vs 200 000 dwarves ?

[Zigûr]

Originally Posted by Rhod the Red

If I recall precisely, we have to specification of the reason Gandalf first visited Moria. So maybe he was sent by Saruman, or the White Council as a whole, to investigate that very matter.

The first time Gandalf went to Moria he was looking for Thráin: "Yet it will not be the first time that I have been to Moria. I sought there long for Thráin son of Thrór after he was lost." (The Fellowship of the Ring p.289)
I've always found this a very curious point, because I always got the impression that Gandalf had stumbled upon Thráin quite by accident in Dol Guldur and that given that he was only able to reason out the Dwarf's identity much later (Thráin couldn't remember his own name) it seems odd that Gandalf had actually gone searching for him. That being said, perhaps in his efforts to see if Smaug could be dealt with he did at some point deliberately seek Thráin - just in the wrong place.
In this way it would appear that Gandalf's presence there wasn't enough to stir the Balrog; he learned nothing of it on his first journey - could the Ring have been involved? Presumably Gandalf's power was more "veiled" on his first visit. It was when the Fellowship passed through that the Balrog appeared; I wonder if it had more to do with the Ring or with Gandalf using his power a bit more liberally on the second occasion.
I get the impression that since Durin's Bane seemed content to lurk in Moria - and because no one seemingly knew what a truly terrible being it was - people like the White Council never risked action against it.