The Silmarillion

Angrod son of Finarfin was the first of the Exiles to come to Menegroth, as messenger of his brother Finrod, and he spoke long with the King, telling him of the deeds of the Noldor in the north, and of their numbers, and of the ordering of their force; but being true, and wisehearted, and thinking all griefs now forgiven, he spoke no word concerning the kinslaying, nor of the manner of the exile of the Noldor and the oath of Fëanor. King Thingol hearkened to the words of Angrod; and ere he went he said to him: 'Thus shall you speak for me to those that sent you. In Hithlum the Noldor have leave to dwell, and in the highlands of Dorthonion, and in the lands east of Doriath that are empty and wild; but elsewhere there are many of my people, and I would not have them restrained of their freedom, still less ousted from their homes. Beware therefore how you princes of the West bear yourselves; for I am the Lord of Beleriand, and all who seek to dwell there shall hear my word. Into Doriath none shall come to abide but only such as I call as guests, or who seek me in great need.'

Now the lords of the Noldor held council in Mithrim, and thither came Angrod out of Doriath, bearing the message of King Thingol. Cold seemed its welcome to the Noldor, and the sons of Fëanor were angered at the words; but Maedhros laughed, saying: 'A king is he that can hold his own, or else his title is vain. Thingol does but grant us lands where his power does not run. Indeed Doriath alone would be his realm this day, but for the coming of the Noldor. Therefore in Doriath let him reign, and be glad that he has the sons of Finwë for his neighbours, not the Orcs of Morgoth that we found. Elsewhere it shall go as seems good to us."

But Caranthir, who loved not the sons of Finarfin, and was the harshest of the brothers and the most quick to anger, cried aloud: 'Yea more! Let not the sons of Finarfin run hither and thither with their tales to this Dark Elf in his caves! Who made them our spokesmen to deal with him? And though they be come indeed to Beleriand, let them not so swiftly forget that their father is a lord of the Noldor, though their mother be of other kin.'

Then Angrod was wrathful and went forth from the council. Maedhros indeed rebuked Caranthir; but the greater part of the Noldor, of both followings, hearing his words were troubled in heart, fearing the fell spirit of the sons of Fëanor that it seemed would ever be like to burst forth in rash word or violence. But Maedhros restrained his brothers, and they departed from the council, and soon afterwards they left Mithrim and went eastward beyond Aros to the wide lands about the Hill of Himring. That region was named thereafter the March of Maedhros; for northwards there was little defence of hill or river against assault from Angband. There Maedhros and his brothers kept watch, gathering all such people as would come to them, and they had few dealings with their kinsfolk westward, save at need. It is said indeed that Maedhros himself devised this plan, to lessen the chances of strife, and because he was very willing that the chief peril of assault should fall upon himself; and he remained for his part in friendship with the houses of Fingolfin and Finarfin, and would come among them at times for common counsel. Yet he also was bound by the oath, though it slept now for a time.

Now the people of Caranthir dwelt furthest east beyond the upper waters of Gelion, about Lake Helevorn under Mount Rerir and to the southward; and they climbed the heights of Ered Luin and looked eastward in wonder, for wild and wide it seemed to them were the lands of Middle-earth. And thus it was that Caranthir's people came upon the Dwarves, who after the onslaught of Morgoth and the coming of the Noldor had ceased their traffic into Beleriand. But though either people loved skill and were eager to learn, no great love was there between them; for the Dwarves were secret and quick to resentment, and Caranthir was haughty and scarce concealed his scorn for the unloveliness of the Naugrim, and his people followed their lord. Nevertheless since both peoples feared and hated Morgoth they made alliance, and had of it great profit; for the Naugrim learned many secrets of craft in those days, so that the smiths and masons of Nogrod and Belegost became renowned among their kin, and when the Dwarves began again to journey into Beleriand all the traffic of the dwarf-mines passed first through the hands of Caranthir, and thus great riches came to him.