Powys Wenwynwyn or Powys Cyfeiliog was a Welsh kingdom which existed during the high Middle Ages. The realm was the southern portion of the former princely state of Powys which split following the death of Madog ap Maredudd of Powys in 1160: the northern portion (Maelor) went to Gruffydd Maelor and eventually became known as Powys Fadog; while the southern portion (Cyfeiliog) going to Owain Cyfeiliog and becoming known, eventually, as Powys Wenwynwyn after Prince Gwenwynwyn ab Owain, its second ruler.