Everyone knows that a mile is 5,280 feet. 1,760 yards. But that was just the Romans. In the British Isles, the Irish Mile was 6,720 feet and the Scottish Mile 5,952 ["We think na on the lang Scots miles" - Robert Burns, Tam o' Shanter].
Enter the 9th century Persian astronomer Ahmad ibn Muhammad ibn Kathir al-Farghani [which name is pretty much a family tree in itself]. He used a measurement of somewhere between 6,500 and 7,000 feet for his "Arabic Mile".
Which brings us to Christopher Columbus. Columbus believed the earth was round; also that Asia was a very long (west to east) continent and he set out across the Atlantic fully expecting to make landfall in Japan before long. Using al-Farghani's "mile" he calculated the length of Asia as being around one-third more than it actually is, so it was a lot further away than he thought. It's not known whether his first words to the Lucayan people he met on the Bahamian beach of Guanahani were "Kon'nichiwa, Kyōto e no michi o oshiete moraemasu ka?"**
If you've ever wondered why it takes so long to walk the 136 miles from Dublin to Cork, now you know. Mother Goose knew about different miles:
There was a crooked man, and he walked a crooked mile,
He found a crooked sixpence against a crooked stile;
He bought a crooked cat which caught a crooked mouse,
And they all lived together in a little crooked house.
** こんにちは、京都への道を教えてもらえますか?