The date of authorship of the Lament is open to question, though it must clearly have been composed some time after the Darkening of Valinor, which it described. We're told that it was known to all the Eldar, which raises difficulties as many of the Eldar left Valinor almost immediately after the destruction of the Trees, and Elemmírë can hardly have had time to create the Lament before this happened. More likely, the tale was composed in the years after the Darkening, and later brought to Middle-earth from Aman, perhaps by the armies of the Valar at the end of the First Age.