Open plot without pattadar passbook

I want to buy an open plot so one mediator showed me plot and when I ask for pattadar pass book and title deed of the landlord he is telling that as this agriculture land has been layout long back and he doesn't have contact number/information of the actual agricultural landowner. But this plot has been purchased by X person and then he did GPA to Y. Now the issue is with mediator/broker, he is telling that Y doesn't have these docs and when I ask for Pahanis he is telling the same that owner (person Y) doesn't have pahanis but you can get it from the municipality. I have a doubt that shall I proceed and purchase or not?