Following his father 's death , Pryderi became ruler of the seven cantrefs of Dyfed .
Following his father 's death , Pryderi set about expanding his territories by conquering Ystrad Tywi and Ceredigion .
Following his father 's death , Pryderi became ruler of the seven cantrefs of Dyfed and set about expanding his territories by conquering Ystrad Tywi and Ceredigion .