Know Your LotRO Lore: Khazad-dum in the Third and Fourth Age

Luckily, Sauron's hatred was not enough to drive out the Dwarves and they enjoyed a peaceful recovery period that lasted 1300 years. A second golden age for the Dwarves was not in the cards though, as their mithril veins became exhausted, leading to a shortage of tradable goods for food. To top it all off, in the year 1980, miners in Khazad-dûm dug too deep in their desperate search for mithril that they disturbed an ancient balrog who would ultimately lead to their demise. This long forgotten demon rose from its slumber to defeat Durin VI in that year, and his son Nain the following year.

The balrog, now known as Durin's Bane, forced the Dwarves to abandon their once-great underground kingdom, allowing the Orcs an easy way to take it over. It was at this point that the Elves renamed the caves Moria, meaning "The Black Chasm."

Eventually, in the year 2790, one of Durin's own descendants, Thror, vowed to re-enter his ancestral home and take back Khazad-dûm. He was defeated by the Orc chieftain Azog in what would spark the infamous War of the Dwarves and Orcs. Several years after the Dwarven victory in that war, Thror's son Thrain II set out to continue where his father had failed, but was convinced to cease his journey and listen to the prophesies of King Dain. He was told that a power greater than the Dwarves must arrive before Durin's people could return to Khazad-dûm.

At one point towards the close of the Third Age, a Dwarf named Balin led a team to reopen the city, against King Dain's wishes. As expected, the colony failed, Balin was defeated and the colony was destroyed. King Dain was then visited by a messenger from Mordor offering to return three of the seven Dwarf Rings and all of Moria if he would help find the One Ring. The king refused.

By the time the Fellowship passed through, it was the year 3019 and most of the area was in shambles. Durin's Bridge is where Gandalf faced Durin's Bane, eventually fulfilling King Dain's prophecy by facing and destroying the evil balrog. Durin's Bridge was destroyed in the process, restricting access to the mines from the east.