Need Help On THE MAHARASHTRA RESTORATION OF LANDS TO SCHEDULED TRIBES ACT

I am a farmer & having land of 3.5 acre from 25kms from Amravati. My farm was purchased by my father in 1986. A few days back we receive a legal notice from one fellow claiming for my farm, with whom we never deal. He is claiming himself as ADIVASI & land was sold by his father in 1979 to another person. After application, we receive land record which show his father's possession period from 1971- 1979. I had some doubts which are as follows 1. mentioned land was not purchased from ADIVASI by us 2. There is neither remark of ADIVASI LAND on ur 7/12 nor on sales dead or any documents 3. we are paying tax for this land from 1986. 4. we are belong to TELI community (OBC) & mentioned land was belong to TELI community person till 1971 which he sold to so called ADIVASI. SO HOW THAT LAND IS ADIVASI LAND. 5. Farming is only income source of mine so how can I protect it. Is there any govt policy to protect me as I am ALPBHUDHARAK (very min land owner) 6. is there any time limit for land deman