The subject of this article originates from non-canonical sources. To find out about what is considered "canon" see LOTR:Canon.
Nordinbad is one of the locations in the game The Lord of the Rings: War in the North. It is a Dwarven fortress hidden deep within the Grey Mountains, serving as a place of isolation and refuge for the Dwarves of Durin's Folk. They lived around an underground lake known as Azan-zâram. Gorin of the Longbeards is the ruler of these secretive people.
In the Third Age, during the War of the Ring, Nordinbad served as a refuge for the Dwarves of the Grey Mountains. Agandaur declared war on Nordinbad, as well as all other Free Folk in the North of Middle-earth.
As the Right Hand of Sauron, Agandaur gathered armies of Orcs all over the north, as well as Goblins, Trolls, and several other foul things. It is revealed that Agandaur arrived at Nordinbad under parley, and told them to turn over Nordinbad to him and he will spare them. The Dwarves, of course, refused. Angered, Agandaur warned them that they would all be destroyed by the fiery doom that awaited them.
When Agandaur was gathering Orcs at Mount Gundabad, the Dwarves led by prince Nordri went to activate an ancient weapon deep within the mountain itself. With the help of three warriors set out from Rivendell named Eradan, Farin and Andriel, Nordri and his friend Bruni were able to activate this weapon, killing many orcs. With the help of the Great Eagle Beleram, as well as his companions Baranthor and Armenel, the heroes were able to escape and return to Nordinbad.
There, lord Gorin rewarded Eradan, Andriel and Farin for their help, and told them of their negotiations with Agandaur. When they mentioned the fiery doom, Gorin feared that he referred to a Dragon who lives in the mountains eastward named Urgost. Farin, Eradan and Andriel set out to find the wizard Radagast the Brown in Mirkwood to see if he can help them find where Urgost is based.
During the heroes' quest to find the dragon, Agandaur laid a siege on Nordinbad. The dwarves were hit hard, many killed or wounded. Gorin was wounded and Nordri's friend Bruni was killed. Eradan, Farin and Andriel returned and dealt with the remaining forces of Agandaur: Orcs, Uruk hai, goblins, trolls and Men of Carn Dum. Beleram was injured badly, whilst Baranthor and Armenel were killed.
When the battle ended, Eradan, Andriel and Farin received a reward from Gorin for saving Nordinbad. Also, they set out to end Agandaur for good at his stronghold of Carn Dûm, the former fortress of the Witch-King and part of their bargain with Urgost.
Eventually, the three heroes defeated Agandaur, and with his death Sauron fell as well. Nordinbad was not only safe, but so was every other land in Middle-Earth. With Agandaur defeated, Urgost can lay claim to Carn Dûm, and the Dwarves of Nordinbad are safe.
Following the conclusion of the War of the Ring, it is possible that the Dwarves of Nordinbad regained contact with the Dwarves of Erebor. In War in the North, after Gloin was informed of the existence of Nordinbad from the protagonist, he wanted to set up relations with the lost folk of Longbeards.