 By the end of the 13th century, it had become such an important trading center that some estimates credit its trade in ale, wine, wool, and hides with 70% of Gwynedd's tariff revenue.It also held two annual fairs and maintained a herring fishery.When Llywelyn the Great's wife Joan, the daughter of King John of England, died in 1237, her body was buried at Llanmaes and a Franciscan monastery constructed at Llywelyn's expense at the site.