Ownership of land.

Sir, almost 50 years back my uncle purchased a piece of land. Also a house was constructed over there by my uncle. That means land was under our pocession since last 50 years. All the documents and survey papers shows our ownership of the land. Now the house has been demolished because of getting old. Once the wall broken the heirs of the seller claims again the ownership of the land leaving behind a dispute. Actual person who sold the land never claimed in last 50 years while he was alive. Now both actual seller and purchaser have died, his heir have started dispute. Disputed part of the story: The seller of the land were two brothers. The land had been sold when they were together. The paper reflects only one person's name as a seller. Now they are separate family and property has been distributed between them. This dispute was raised by second person's sons whose name was not mentioned in the paper saying that my father has not sold and my unlce has sold my part of the land also. What is the legality in the matter? What should i do for the repocession of my 50 years old land?