Tolkien himself was unsure if we were in the 6th or 7th age --- I doubt if there would have been much gain; and I hope the, evidently long but undefined, gap*

Tolkien himself was unsure if we were in the 6th or 7th age --- I doubt if there would have been much gain; and I hope the, evidently long but undefined, gap* in time between the Fall of Barad-dûr and our Days is sufficient for 'literary credibility', even for readers acquainted with what is known or surmised of 'pre-history' I imagine the gap to be about 6000 years : that is we are now at the end of the Fifth Age, if the Ages were of about the same length as S.A. and T.A. But they have, I think, quickened; and I imagine we are actually at the end of the Sixth Age, or in the Seventh. Source - The Letters of J.R.R. Tolkien, Letter 211