Avengers: Infinity War finally introduced viewers to the dwarf homeworld of Nidavellir; and, while the name may have been considered a made-up world by Drax, this Realm has actually been teased in all three of the Thor movies to date. In fact, it's even referenced in two of the official tie-in comics as well.

Nidavellir played a crucial role in Avengers: Infinity War. It turned out that Eitri, King of the Dwarves, had been forced to make the Infinity Gauntlet for Thanos - a powerful device that could be used to harness all six Infinity Stones in conjunction. Thor was able to persuade Eitri to seek a kind of revenge against the Mad Titan, and as a result the God of Thunder left Nidavellir armed with a new weapon, Stormbreaker, one greater than any other Eitri had ever made for the Asgardians before.

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But here's the interesting thing; while this was the first time we've seen Nidavellir on the big screen, this particular Realm has been teased throughout the entire Thor trilogy. According to the first Thor film, Mjolnir itself was created by the Dwarves. Thor's hammer was "forged in the heart of a dying star" - that's the Neutron Star we saw in Avengers: Infinity War. Technically, that means every single time you see Mjolnir in action, you get a sense of the power of Dwarven weapons. In the comics, most Asgardian relics were created at Nidavellir, including the swords wielded by Heimdall and Sif, as well as Odin's spear. That's probably true in the MCU, especially given that Heimdall's blade, Hofund, appears to have been created as part of the Bifrost mechanism. That's the kind of complex metalwork you expect from the Dwarves.

Nidavellir is one of the Nine Realms of the cosmos, worlds that are mysteriously bound together in the so-called "World Tree." Although it wasn't named in Thor, there is a blink-and-you'll-miss-it reference in Thor: The Dark World, when Erik Selvig scrawled a prophecy of doom on a blackboard. Look closely, and you can see the names of several of the Realms, including Nidavellir.

So just what happened to Nidavellir? It appears that the Dwarves preferred to keep themselves separate from the rest of the Nine Realms, and created weapons for Asgard in repayment for protection from marauders. Unfortunately, in the first Thor film the Rainbow Bridge was shattered, and Asgard was briefly unable to make good on its promises. According to 2014's Thor: The Dark World Prelude comic, the Troll Lords had long coveted Nidavellir's forges, and they saw their opportunity to strike. When the Bifrost was finally repaired, Thor led the armies of Asgard out into the Nine Realms to restore peace. Disturbingly, though, there's no evidence they ever got to Nidavellir before the events of Thor: The Dark World. In the aftermath of that film, Loki took charge, and Asgard's forces were withdrawn. As was noted in Thor: Ragnarok, the cosmos fell into chaos in Asgard's absence.

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And then Thanos came to Nidavellir, and he forced the Dwarves to construct the Infinity Gauntlet. According to the Russo brothers, the post-credits scene of Avengers: Age of Ultron is set on Nidavellir, and shows Thanos don the Gauntlet for the first time. The Mad Titan's usual modus operandii is to slaughter half of every world he visits, but he viewed the Dwarves as too dangerous; after all, they knew what they had made for him. He had them wiped out, all but their King, Eitri, whose hands he took so he shouldn't have been able to forge anything ever again. When Thor finally arrived on Nidavellir, it was a dead place, with the Neutron Star's fire dying without the care of the Dwarves to sustain it.

This is the beauty of the Marvel Cinematic Universe; although Nidavellir was only introduced in Avengers: Infinity War, the Dwarven Realm was already clearly established in the shared universe well before then. And given that Eitri is the only person left who can make weapons capable of harming Thanos, the Avengers may need to call upon Nidavellir again.

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