Partition suit - is this valid-

If the property is ancestral, the brother has certainly a share in it. Try to work out an amicable settlement.

The property in question is stated to be ancestral in nature and even otherwise if it was originally in the name of grandfather, all the sons of the grandfather have share in the property. As a coparcener of the Hindu family your uncle can seek partition of the ancestral property. The division of the property will be conducted by the court by appointing advocate commissioner for the job. The property tax is being paid hence the record of the property exists with the authorities.

Now that you have enjoyed enough, give the rightful share to the legal heir (your uncle) and settle the issue amicably.   He has a right, whether the enjoyed the profit or stayed there are not relevant, as one co-sharer can enjoy the possession in trust for others.  Simply because you have enjoyed the property for 50 years, you can not claim the property as your own, unless the family was seaparated 50 years back, and you are enjoying the property on your behalf and on your uncle's behalf.

Thanks for all the valuable advises.

1. so,even if no doc exist,does the first still occupant becomes the rightful owner in case of grama natham land?. if yes,and it  is my great grandparents in that case who were 1st occupants,  will it still be considered as ancestral in nature,and does all the laws of partition suit gets applicable even on such lands? reason because, i was told that the current possession holder(especilly when no mutation done by ancestors or no partitio was made) becomes the rightful owner of the property n case of grama natham land..is it not so? the only doc we have is a registerd deed created under the name of my great grandfather for a piece of land (for 1/4 of what it is today) and rest of the land were eventually occupied and in possession for last 50 years by my grandfather. my father was all along staying wtih his parents here until their death nd now continung the possession with his family. wil the advocate commmissioner be able to trace and get to the root of the orginal owner of the land / is that practically feasbile?

@Prasad ji-
when you say unless separated for 50 years, you mean by way of partition suit that is registered or by mere phsyical separation. if that is the case, the later is true in our case. there is no partition as such done so far and so still conisdered joint in possession and it is just that my uncle has moved out long back at his young age. we are seriously considring to get the mutation done now to my dad name and not sure if that will have any standing without a registerd doc or Will due to this new partition suit case.

some of the contacts i spoke mentinoed not to give any reply to the notice and let it go with their evidence(which we doubt my uncle has any such parent doc for property) and says that this case will not have a standing because of lack of title /docs and we should not be bothered about.

You have to establish to the satisfaction of court that there was an earlier partirtion, and through that partition your father has received exclusive possession and enjoyment separately in his name and provide evidence to that extent.  Not having mutation and others are against such statement.  Getting mutation is not easy now, you have to provide title deed that staters that your father has acquired the property in his name with such legal heir list and do not jump into conclusions and take action.   These issues are beyond advises in open forum, and posting of all this in open forum may go against your interests if they are produced in Court.  Always confide in a trusted local advocate and do not get confused and deal with the situation when the problem comes and make preparation.   None of the members in the forum advise you to enjoy the property for further period, after enjoyed 50 years exclusively, and depriving the legitimate benefits to a person legally entitled as a right by him.