Moria, also known as Khaza-dum, was an underground dwarf city with mines and tunnels running under the Misty Mountains. It was founded by Durin the Deathless who became Durin I (and several other rulers of Moria after him would take the name Durin). In the Third Age the dwarves uncovered the Balrog (of Morgoth) and the city was abandoned. Sauron placed Orcs inside and the dwarves fought to reclaim it, but did not enter for fear of the Balrog until many years later. Balin who travels with Bilbo in The Hobbit reestablishes the city but once again it falters when it is overun by orcs. Following this, the Fellowship makes its way through Moria unaware that the city had fallen.