[1] Its name is preserved by the barony of Tirerril in southeast County Sligo.
It is named after Olliol, one of the sons of Eochaid Mugmedon and half brother of Niall of the Nine Hostages, from whom descended the Uí Ailello, a branch of the early Irish dynasty known as the Connachta.
The Uí Aillelo dynasty sank into obscurity at an early date.
but the name is preserved as the tuath[2] of Tir Ollíol (Tirerril).
They later split into two groups, one based in Collooney and Ballindoon (Tirerril), and the other in Ballymote (Corran).