Massacre of the Dwarves

"Three hundred dwarves lived on this ring. I thought if I did what he asked, they'd be safe. I made what he wanted: a device capable of harnessing the power of the stones. And he killed everyone anyway."

- Eitri to Thor The Massacre of the Dwarves was the result of a mass purge initiated by Thanos as means to prevent the future forging of advanced weaponry on Nidavellir.