Under Illtud and his successors, Côr Tewdws and the monastery grew in reputation both as the origin of many prominent Celtic evangelists and as a major centre of scholarly education. As such, it began to attract scholars from across the Celtic and wider world. The college itself was said to be the oldest in the world, consisting of seven halls, 400 houses and more than 2000 students at its peak, including seven sons of British princes, and scholars such as St. Patrick, St. Paul Aurelian, the bard Taliesin, Gildas the historian, Samson of Dol, and St. David are believed to have spent some time there. Samson was known to have been summoned by Dyfrig to join the monastery in 521 and he was briefly elected abbot before leaving for Cornwall. King Hywel ap Rhys (d. 886) was buried at the monastery.