East-gate of Moria

The East-gate of Moria, also known as the Dimrill Gate or the Great Gates, was the oldest and principal entrance to the Dwarven kingdom of Khazad-dûm.

Second Age and prior
The gate was presumably first made when Durin the Deathless first came to the caves which would eventually become known as Moria, or Khazad-dûm. It would remain the main, and perhaps only, entrance to Moria until the creation of the Doors of Durin in the Second Age.

Third Age
In the year TA 2790, following the fall of Moria to goblins, Thrór, king of Durin's Folk, and a single companion named Nár journeyed to Moria. Despite Nár's pleas to the contrary, Thrór entered the East-gate with the intent to reclaim the kingdom. Nár waited for several days until at last, his fears were confirmed when Azog, the chief of the goblins in Moria, produced Thrór's decapitated body and sent Nár back to his people as a messenger. This act instigated the War of the Dwarves and Orcs, which culminated nine years later at the Battle of Azanulbizar, in the same location in which it began before the East-gate. The doors of the gate were destroyed during the battle, and though the goblins were defeated, no attempt to retake Moria was made due to the presence of Durin's Bane.

Later, in TA 2994, when Balin's expedition to reclaim Moria was attacked by goblins, the gate was barred but soon broken through, forcing the members of Balin's company to retreat farther in, where they were eventually slain.

In TA 3019, the Fellowship of the Ring passed through Moria, and following their encounter with Durin's Bane, fled through the East-gate into Dimrill Dale.