White's Warp

In T.H. White’s The Once and Future King,
Young Arthur, who has yet to take the throne,
Meets Robin Hood, with men and everything.
Already, they have gotten widely known.
It seemed to me that something was awry.
I looked online for legends of the two,
And sure enough, the timelines don’t comply,
As Robin’s seven hundred years too new.
Imagine if a future author wrote
That Ethan Allen met a young El Cid.
It doesn’t take that long a search to note
They couldn’t have, as scholars have agreed.
Of course, I would be silly to insist
The Wart and Robin ever did exist.