My great grandfather's property was divided amongst his three sons on a mutual consensus without pre

My great grandfather's property was divided amongst his three sons on a mutual consensus without preparing any legal document. Now, my late grand father also didn't prepare any legal will about distribution of property among his seven sons. My father passed away approximately 30 years ago and my mother brought me up with my maternal grandfather's support. Now my mother and myself have been asking our uncles to divide the property equally and give our share. The request has always gone unheard and nothing has happened as yet. They are selling the properties as per ther wish. Would like to know what is legal way to have this resolved.