HistoryEditA high road ran between Ost-in-Edhil and Khazad-dûm, built during the Second Age by the Elves of Eregion and The Dwarves of Khazad-dûm, it enabled an unprecedented friendship between the two peoples and would last as long as their realms did. Eregion's jewel smiths, under Celebrimbor, achieved the highest levels of craftsmanship since Fëanor, and the Dwarves of Durin III's work in Mithril enamored all who beheld them as trade between the two realms grew. It would be well into The Fourth Age until another friendship between Elf and Dwarf would come close to this alliance.
"Eregion was nigh to the great mansions of the Dwarves that were named Khazad-dûm, but by the Elves Hadhodrond, and afterwards Moria. From Ost-in-Edhil, the city of the Elves, the highroad ran to the west gate of Khazad-dûm, for a friendship arose between Dwarves and Elves, such as has never elsewhere been, to the enrichment of both those peoples. In Eregion the craftsmen of the Gwaith-i-Mírdain, the People of the Jewel-smiths, surpassed in cunning all that have ever wrought" 
"...they saw below them a deep and narrow channel. It was empty and silent ... but on the near side there was a path, much broken and decayed, that wound its way among the ruined walls and paving-stones of an ancient highroad." 
"There are the Walls of Moria,' said Gandalf, pointing across the water. 'And there the Gate stood once upon a time, the Elven Door at the end of the road from Hollin by which we have come." 
"Here the Elven-way from Hollin ended. Holly was the token of the people of that land, and they planted it here to mark the end of their domain; for the West-door was made chiefly for their use in their traffic with the Lords of Moria."