Property division problem

Dear Sir/ Madam, This is bring your kind notice that I Shree Parash Nath Upadhyay, Aged 78 Year’s Residence at M/s. Ajanta Motor Works Opp- Sarbajanin Kalibar, A.T. Road Tinkonia, Tinsukia, Assam-786125 Contact:- 9085284025, 7896485534 Have six brothers, except two including me, rest four are residing at our native place Village- Kachnar, Post- Kachnar PS. Siswan, Via- Gangpur Siswan Dist. Siwan, Bihar Now a day I have been tortured mentally by my two younger brother Mr. Satrudhan Upadhyay and Mr. Sambhu Nath Upadhyay for long times, They have captured my land at our native place Bihar and farming over there for about to more than 20 years and whenever I ask to vacate my land or give my share which is legally, they are brutally abusing and threatening to beating/kill me and my family whenever I’ll come to Bihar, Let me brief some details about the property, this property is our forefather and it has not been divided legally, its divided by mutual understanding. And I am residing Assam since 1972 and have been going some time in my village (Bihar) so therefore I don’t know about the protocol of Bihar and do not have any papers of property so my brothers taking advantage for this. I have done everything for my brothers, destroyed my childhood my career). I am poor & old man and cannot fight with them, so here you are requested to advise me how to take my share legally from my brothers.