|History of Arda|
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The Third Age was held to have ended when Elrond left Middle-earth on 29 September of T.A. 3021. There is no information on more than the first few centuries of this age, so it is not known when it ended, if it ever did, although it was probably shorter than 3 millennia.
This age was marked by the recovery of the Númenorean kingdoms of Arnor and Gondor, while the House of Durin retook Moria until the race of Dwarves failed. The Last Ship of the Elves, carrying Círdan, Celeborn, and all remaining Elves of the First Age left Middle-earth some time after Fo.A. 171. Eventually that would lead to the final Dominion of Men over Arda, coming together with the total waning of the Elves and other dwindling races, such as the Ents and probably the Dwarves.
Tolkien said that he thought the distance between the end of the Third Age and the 20th century A.D. was about 6,000 years, and that in 1958 it should have been around the end of the Fifth Age if the Fourth and Fifth Ages were about the same length as the Second and Third Ages. He said, however, in a letter written in 1958 that he believed the Ages had quickened and that it was about the end of the Sixth Age/beginning of the Seventh.
Reckoning of years
Not all calendars in use in Middle-earth at that time reset their count of years to Fo.A. 1 in the same year, on the same date, or indeed at all. As such, years given for certain events in the Fourth Age differ according to the calendar used.
The Shire-reckoning is the calendar system used for all dates in the Red Book, with S.R. 1 corresponding to T.A. 1601. Years in Shire-reckoning did not restart at the end of the Third Age, rather it continued uninterrupted from S.R. 1421 to S.R. 1422, and "in so far as the Hobbits took any account of the change of Age, they maintained that it began with 2 Yule 1422." This means that S.R. 1422 is also T.A. 3022 and Fo.A. 1 as far as dates in the Red Book are concerned.
However, in Gondor and the rest of the Reunited Kingdom outside the Shire, the New Reckoning calendar entered use starting in T.A. 3019. Under this calendar, 25 March T.A. 3021 is the first day of Fo.A. 1, some 9 months earlier than the new year in the Shire. The Shire Calendar and the New Reckoning begin their years on different days: 2 Yule for the Shire and 25 March for the rest of the Reunited Kingdom.[note 1]
There are few dates given in the legendarium that require the reader to account for this difference, because most dates of the Fourth Age are already explicitly expressed in terms of the Shire Reckoning. For example, Legolas and Gimli's departure from Middle-earth is given as S.R. 1541. The exceptions are both from the Note on the Shire Records and are as follows:
- Tolkien explains that the text of The Lord of the Rings descends from a copy of the Red Book made in Gondor that bore the note "Findegil, King’s Writer, finished this work in IV 172." The accompanying text notes the equivalent year S.R. 1592, which is Fo.A. 171 in the Shire Reckoning, so this note must have been written with regard to the New Reckoning calendar before 7 Narvinyë.
- In the same paragraph, Tolkien refers to Peregrin Took's retirement to Gondor in "IV 64." We are told elsewhere that Peregrin and his companion Meriadoc Brandybuck arrived in Gondor sometime between the autumn and the ending of S.R. 1484, which is Fo.A. 63 in the Shire Reckoning. As such, the stated "IV 64" must be in reference to the New Reckoning calendar, again, prior to 7 Narvinyë.
- J.R.R. Tolkien, The Lord of the Rings, Appendix D, "The Calendars"
- J.R.R. Tolkien; Humphrey Carpenter, Christopher Tolkien (eds.), The Letters of J.R.R. Tolkien, Letter 211, (dated 14 October 1958).
- J.R.R. Tolkien, Christopher Tolkien (ed.), The Peoples of Middle-earth, "Of Dwarves and Men"
- J.R.R. Tolkien, The Lord of the Rings, "Prologue", "Note on the Shire Records"
- J.R.R. Tolkien; Humphrey Carpenter, Christopher Tolkien (eds.), The Letters of J.R.R. Tolkien, Letter 338, (dated 6 June 1972)
- J.R.R. Tolkien, The Lord of the Rings, "Prologue", "Concerning Hobbits"
- J.R.R. Tolkien, The Lord of the Rings, Appendix B, "Later Events Concerning the Members of the Fellowship of the Ring"