After the establishment of the land of Eregion in the year II 750, the followers of Celebrimbor became famous for their works of art and craft. They were known as the Mírdain, the jewel-smiths, and the people of that country came to be known as the People of the Jewel-smiths. Their skill gained them the friendship of the Dwarves of nearby Khazad-Dűm, who valued such artistry, but their fascination with the making of things was to bring about their downfall.
Nearly five hundred years after Eregion's foundation, a mysterious being appeared among its people. Calling himself Annatar, he had knowledge and skill beyond even that of the Mírdain, and he offered this knowledge freely to the People of the Jewel-smiths. They accepted his offer, and for some three hundred years more Annatar taught them. Eventually, their skills were great enough the begin forging Rings of Power, of which they made many. Their greatest works were the Three Rings Narya, Nenya and Vilya. Through these Rings, they discovered to their horror that 'Annatar' was none other than their ancient enemy Sauron, who had corrupted their great work to his own ends. Sauron was enraged at his discovery, and his armies swept across Eriador and into Eregion, wiping out the jewel-smiths and their people.
Ost-in-Edhil, the city of the Elves in Eregion
Ost-in-Edhil was the great Elvish nation of the mid-Second Age. It was here that the House of the Mírdain stood, and here too that the Rings of Power were forged by Celebrimbor and the Mírdain. The city stood for nearly a thousand years, but was ravaged by Sauron during his invasion of Eriador.