this was my first thought. you may need advice from an attorney as well. weird ***** can pop up when you buy land. a few years ago i bought a couple of acres for future plans. what a mess. it took almost a year and tons of attorney fees to push it through. it was part of a trust, and they had a shocking about of trouble hammering out the specifics. after the purchase went thought, and it was being evaluated for a project, i was lucky to find out that it was, "archaeologically sensitive" land. yup. it was in the ballpark of native american land, and it had to go through a stage 1 evaluation to make sure no specific signs inhabitation were present. fortunately nothing was found, and we could move forward.
that being said, buy as much as you can. I had an opportunity to buy another 8 acres behind it, and after all of the trouble i decided not to. i wish i had.