Buying a land under dispute is virtually everywhere but most common in crowded urban areas where most land have being sold.
One of the first method is to ask people living around the area about past history of people that have once shown interest on the land or those that have once paid for them, what happened to them when they started work on the land? did they suddenly faced oppositions or everything just collapsed on their head and they have to live the site entirely? these are what people living close to that land can tell you about.
The engagement of competent lawyer to do a thorough check on the documents of the land is essential to avoid falling into such problems. Lawyers do a thorough check on the land and legal history pertaining to the land.

http://buildingcontractorsecrets.com/2007/10/08/how-to-detect-land-under-dispute-and/