The Rivers and Beacon-Hills of Gondor is a historical-etymological essay written by J. R. R. Tolkien sometime after June 1969.
This essay has never been published in its entirety, although parts of it were published in Unfinished Tales, and the remaining parts were published in the periodical Vinyar Tengwar, issue number 42 in 2001. The Vinyar Tengwar article was based on a version which was intended for publication by Christopher Tolkien in The Peoples of Middle-earth but was not included owing to space constraints, although it was mentioned in the book.
However, as with many of his late works, Tolkien never got to finish the essay, abandoning it while in the middle of the discussion of the beacon-hill Halifirien. However, based on what can be gleaned from this, it seems it is at this point that Tolkien decided to introduce the idea of having the tomb of Elendil in Halifirien, which became an essential element in the work Cirion and Eorl. Therefore from Paul Bibire's query arose the history of Halifirien and Elendil's tomb.