We have no canonical record of Ciryon's date of birth. The year of III 3379 given here comes from a genealogical chart in volume I2 of The History of Middle-earth showing Isildur and his sons with their dates of birth. To complicate matters, Ciryon does not appear by name on this chart, and indeed Isildur's three elder sons have quite different names from those given in the published Silmarillion. The date given here is actually for Vëandur, the name of the third son on that chart, whom we take here to be essentially the same character as Ciryon.

Ciryon lived in his father's tower of Minas Ithil for much of his life, until its capture by Sauron in II 3429 (when Ciryon would have been fifty years old). After the loss of Minas Ithil, he escaped into the North with his family, and the rest of his comparatively short life was consumed by his part in the War of the Last Alliance. During this period he would have settled nowhere for long, though he likely spent time in Rivendell while preparations were made for the long march back south to Mordor.

Ciryon's name is not explained, but it seems to be connected with cirya 'ship', and this connection is reinforced by his earlier name Vëandur 'wind follower'. Lacking any detailed description of Ciryon's life, it's hard to be sure whether his name had any particular significance. We do know that he escaped the assault on Minas Ithil with his father, mother and brothers aboard a ship, but whether this meant to imply any special connection to Ciryon's name is unclear.