Ystrad Tywi
Between 1044 and 1055 Gruffydd ap Llywelyn fought Gruffydd ap Rhydderch of Gwent for control of Deheubarth. Following the defeat of Hywel by Gruffydd ap Llywelyn, Gruffydd ap Rhydderch of Gwent was able to "stir up" the minor commote lords of Deheubarth on his behalf, and to call up an army to resist Gruffydd ap Llywelyn, wrote Lloyd. By 1046 Gruffydd ap Llywelyn allied with Sweyn Godwinson, Earl of Hereford, and the two of them campaigned in South Wales against Gruffydd of Gwent. In 1047 the lords of Ystrad Tywi, the heart of Deheubarth and the seat of the Dinefwr family, led an army which totally defeated the 150-strong "teulu", or household guard, of Gruffydd ap Llywelyn, who was narrowly able to escape. In retaliation against the resurgent nobles of Ystrad Tywi and Dyfed, Gruffydd ap Llywelyn devastated those provinces, but "in vain", wrote John Edward Lloyd, "as his authority in South Wales was ... shattered" by Gruffydd ap Rhydderch of Gwent who was now firmly in control of Ystrad Tywi and Dyfed.