If you want the prop to look nice try this:
Get some beige or brownish paper, something which looks weathered. Print out your map.
Then smash it into a paper ball. Flatten out it, smash it some more. Do this like 10 times, differently each time. Fold it over a few different ways, rubbing it against itself to wear it down even more, be prepared for the details you printed out to fade and scratch away. Then, and this is the "dangerous part", grab a bic lighter.
Now get something reasonably heavy and flat, like a skillet or pan or somesuch. Scorch the edges of the paper and then set the flat heavy thing on it to snuff out the flames. Repeat as desired, try some burns in the middle of the map too.
If you have an old fountainpen you can intentionally splatter some ink in an artful fashion, and you might consider dripping some metled candle wax artfully as well.
I've done this a few times for my homebrew fantasyland maps and it always turns out pretty nice.