Being an agricultural land, as per prevailing laws, all of agricultural lands should have an access to the agricultural land or atleast a right of passage (easement rights) to the agricultural land. As per information given by you, i am afraid that someone somewhere is consciously hiding this vital piece of information so as to dissuade you from buying that particular piece of property.
Before you buy, we advise you to check the Record of Rights, Tenancy and Crop Inspection (RTC) at Village revenue officer or at Mandal Revenue office and ask whether there are any passage rights to the property.
In almost 99.5% of the cases, the village revenue officer or the Mandal Revenue officer will have accurate land records as old as 100 years and they will tell you exactly on what is the right of passage to that particular property. they might also tell you how the right of passage or easement right might have been destroyed if the properties (the agricultural land you intend to buy and neighbour's property) had changed hands over the period of time.
Based on your findings from RTC, we can find about the easementry right and file a suit in the court.
if our claim is that right of passage existed previously and now being denied to you, then you can claim for easement rights by prescription .To prove easement rights by prescription we should prove that easement rights existed (as per village records) for at least 20 years prior to its denial.
Even assuming that there were no passage of rights to your proposed agricultural land, you can also can file a suit under Indian Easement Act against the neighbours and ask for right of passage through a Grant.
For your information purpose a grant is given by an agreement executed by a grantor in favour of a grantee for a consideration that will be decided by the court. The grant becomes effective when the grantee has the right to enter upon the grantor's land.
Hope this helps.