Why can't children of the first wife inherit ancestral property?

My father had two wives and 11 children. The first wife has six children (I am the fourth child), and the second wife has five children. My father divided his acquired property among the first wife’s children, but he did not divide any ancestral property among us. This acquired property was bought during the first marriage, and he did not divorce my mother (his first wife). My father gave all ancestral property to the second wife’s children. I would like to know, as the children of the first wife, do we have no right to a share in the ancestral property?