Both the twins were famous hunters, and they dwelt in the wide plains of East Beleriand west of the River Gelion. They were joined there after the Dagor Bragollach by their elder brother Caranthir, and passing south of the Ramdal the brothers settled on the hill of Amon Ereb. They played little direct part in the events of the First Age, though doubtless they aided their brothers in their various battles in pursuit of the Silmarils. Late in the Age, they took part in the assault of the Sons of Fëanor on the refugees at the Mouths of Sirion, and both Amrod and his brother Amras were slain in that fight.
The history of Amrod's name is fraught with complication. According to one tale, his mother Nerdanel originally gave the name Ambarussa ('top-russet') to both the red-haired twins later known as Amrod and Amras. Fëanor insisted that she give them different names, and so she chose Umbarto ('Fated') as a new name for one of the twins. Fëanor was disturbed by this ominous name, and altered it in turn to Ambarto (meaning approximately 'top-lofty').
In versions of the story outside the published Silmarillion, the name 'Fated' was tragically appropriate: Ambarto was burned to death in the firing of the ships at Losgar. In the published he survived, and appears to have taken on an at least partially 'Sindarinized' version of his original name.