In the fictional history of J. R. R. Tolkien's Arda, Nogrod was one of the two western most Dwarven cities, to the south of Mount Dolmed in the Ered Luin of Middle-earth, home to the Dwarven Clan known as the Firebeards.
Known as Nogrod by the Sindar of Beleriand, which translates into modern English as "The Hollowbold", its true name given to it by the Firebeards in their own language Khuzdul was Tumunzahar, of unknown meaning.
Tumunzahar was founded by one of the seven Fathers of the Dwarves, "who were laid severally in deep places, each with his mate." (The Peoples Of Middle-earth). The Firebeards, together with their neighbouring clan, the Broadbeams, then "delved for themselves great halls and mansions, after the manner of their kin, on the east side of Eryd Luin, north and south of Mount Dolmed." (The War of the Jewels).
By V.Y 1250, both clans had established contact with the Sindar of Beleriand, "and soon there was much parley between the peoples."(The War of the Jewels). This contact quickly led to further co-operation between the two races, although portentously, it was the Broadbeams who played a part in the delving of Menegroth at the behest of King Thingol 50 Valian years later, rather than the dwarves of Tumumzahar.
Nevertheless, both clans "trafficked into Beleriand, and they made a great road that passed under the shoulders of Mount Dolmed", through which "much profit they had one of the other", elf and dwarf alike (The Silmarillion).
Where on the one hand the dwarves of Gabilgathol were workers of stone, "none amongst them surpassed the craftsmen of Nogrod" in the crafting of metal, "for they were greatly skilled in such work" (The Silmarillion). The most famous smiths of Tumunzahar was Telchar apprenticed to the legendary Gamil Zirak the old, who made for Thingol what was afterwards known as The Helm of Hador, as well as the knife Angrist and the great sword Narsil. It was probably with the aid of such skilled metallurgists that Eöl of Nan Elmoth "learned much of metalwork, and came to great skill therein", as "he would go at times and dwell as guest in the deep mansions of Nogrod." (The Silmarillion).
After the return of the exiled Noldor to Middle-earth to pursue their war against Morgoth, the Firebeards initially "ceased their traffic into Beleriand" but by F.A 150 they had begun cordial but highly profitable relations with the nearby Noldor of Caranthir's folk. Indeed, by the days of the apocalyptic Fifth Battle, the Noldor "had the help of the Naugrim, both in armed force and in great store of weapons.." (The Silmarillion), although this may have been because "all the traffic of the dwarf-mines passed first through the hands of Cranthir(sic)." (The War of the Jewels).
It was not, however, the Nírnaeth Arnoediad that proved the undoing of Tumumzahar as a power in the world: relations between Tumunzahar and Doriath suddenly soured with catastrophic consequences when Thingol and several Firebeards were killed following an argument that arose over ownership of the Nauglamír, an ancient and precious dwarven necklace that had been crafted into union with a Silmaril, an even more magnificent elvish treasure. The Lord of Tumunzahar responded by assembling a 'great host' that successfully sacked Menegroth, however the host of Tumunzahar was subsequently ambushed and annihilated by a host of Laiquendi led by Thingol's son-in-law, Beren Erchamion, together with a group of Ents.
Like Gabilgathol to the south, Tumunzahar was 'ruined' shortly after, when the Blue Mountains were reduced and broken during the War of Wrath at the end of the First Age. In one version of The Book of Lost Tales, Caranthir attacked and destroyed the Dwarves of Nogrod after their sack of Doriath.
Those Firebeard Dwarves that had not been caught in the 'great host' annihilated at Sarn Athrad then carried on amidst the ruins of their city for another 40 years after the war, when most of these left for Khazad-dûm to merge with its people. Dwarves of one clan or another remained in the mines and mansions of the Ered Luin for thousands of years thereafter, even into the Fourth Age, and if the Firebeards survived as a distinct clan there it would have been in much reduced numbers and circumstances.