Can maternal uncle sell my mothers property claiming rights over
My maternal grandfather had sold the land land to a person X from their village, which my father purchased it from that person X and registered it to my mothers name. my mother passed away in 2002 and the property which till 2010 was in my mothers name has been transferred to my maternal uncles name in 2010. when we asked he told us that my mother had sold it in 2002 just 2 months before her death and even though we all are 3 brothers and 3 sisters ( all 30+ in age) none of our consent was taken. when the documents were obtained regarding the transfer. my uncles have sold the property claiming that my mother had no legal heirs and my uncles are the legal heirs for it as she doesn't have any son or daughter. now they have sold the property to a developer and he has converted it to residential sites and its been sold to others and they have constructed houses in it.
As the property was brought by my father and registered in my mothers name we have the rights over it and what can be the further action to be taken, does the transaction carried out be cancelled and land handed over to us.