The larger of these, Inchcleraun, takes its Irish form, Inis Cloithrín, from Clothra, a figure out of early Irish mythology and sister to Medbh, the legendary Queen of Connaught. Yet by the nineteenth century, the same island was being called Quaker's Island, a prosaic and rather puzzling alternative that points to a much more recent social history, the details of which have largely dissolved from the record. The tension between those two names, one reaching back into pre-Christian myth and the other into the relatively recent past, gives the island an odd double identity before a visitor even sets foot on it.

What draws scholars and curious travellers alike is the ecclesiastical complex on the eastern shore. St Diarmuid, about whom relatively little is widely known, founded a monastery here in the sixth century, placing this island among the earlier wave of monastic settlements that spread across Ireland during that formative period of early Christian activity. Lough Ree, the broad midland lake straddling the counties of Longford, Roscommon, and Westmeath, was well suited to such foundations; its islands offered a degree of seclusion while remaining accessible by water. The site on Inchcleraun is substantial, comprising a cluster of monuments that together constitute one of the more significant early ecclesiastical groupings in the region, with remains spread across the pastureland of the eastern shore.