A license for an image should be directly noted on or near the image (as in a caption). A generic message on a website basically saying "free stuff," to me is not good enough, especially if the site isn't really trustworthy. That site where you got the image has no contact information and has no information about who owns or moderates the site. More than likely it is just a site someone set up to try and make a few bucks and they do so by taking content from other places and stuffing it into their website. If you search for that map on Google, you will find that it appears in quite a few different places. More than likely it is a map that belongs to someone else (perhaps out of a book) and has been copied by others. The fact that they offer it for free, doesn't mean they have any rights to offer it for free.
It very well could be a freely offered map, however, it seems clear to me that the site where you got it from is not the original owner so are not the ones who have a right to put a license on it. If you use it, I'd say you do so at your own risk, though, that risk is probably pretty small.