My uncle is asking for a share in my fathers property what to do.

My father have purchased a plot in jharkhand from a person which is not related to my family .Now my uncle(fathers younger brother) have demanded the partition from that land which my father had purchased with his own money in 1986 but there is no such proof of money because at that time people save money in their home not in a bank .So is there any law by which my uncle take land which is in the name of my father and now he is threating to sue in court . The reason he is sue to court that he is minor at that time and my father had take money from my grandfather to purchase that land .So what is the solution ,is there any means by which he take land from my father or what happened in court if he sued me with the above reason.