The island monastery of Nendrum was traditionally founded in the 5th century by Machaoi, after whom Mahee Island is named, although a later date for the foundation has been suggested. However, dendrochronology has dated a tide mill on the island to the year 619, making this the oldest excavated tide mill anywhere in the world. The monastic site included orchards, gardens, pastures, arable fields, and a guest-house.