An acre (which is still used in the US for land measurement) is roughly the amount of land a team of oxen can plough in a day.

And a league is the distance a person can walk in an hour. The actual distance doesn't actually matter; two places can be 5 leagues away and be at different distances. However, it'll take you 5 hours to get to any of them, be it because different quality roads or elevation changes

Really? an acre is quite small. i find it hard to believe that a team of oxen can't do much more.

And distances (on land and maybe sea too) were long ago measured in interesting units like maybe an arrow shot (distance an arrow can travel) and such like (from my memory of reading legends as a kid, both Indian and probably Western or other ones) :)

E.g.:

https://en.wikipedia.org/wiki/Yojana