Wiston Castle

Until the late eleventh century, this part of southwestern Wales was part of the Welsh state of Deheubarth. The exact administrative structure of Dehubarth is unclear, but it may have been something of an amalgamation of sub-kingdoms, there being a Lord of Dyfed (named Cadifor) in this period, from the earlier line of rulers of Dyfed. Under King William I, Rhys ap Tewdwr, the ruling king of Deheubarth, accepted William's suzerainty, and enjoyed support as a loyal vassal.

In 1088, however, when William died, Rhys, believing his vassalage to be for William's life only, attacked Worcester (in alliance with other powerful rebel vassals); in theory, treason made his lands forfeit. In 1092, Deheubarth was internally destabilised when Cadifor died, and his sons refused to accept the authority of Rhys ap Tewdwr, instead calling for a rival to assume the throne.

Following Rhys' death, the king's agents immediately seized much of Deheubarth; the west of Dyfed was seized by Arnulf de Montgomery, while the north and eastern parts were seized by Normans sailing from Devon - Martin de Turribus and William fitz Baldwin (sheriff of Devon, and son of the previous such sheriff, Baldwin FitzGilbert) respectively.