Tullylish Parish, in Irish "Tulach Lis" meaning `the hill of the fort' or, as stated by Dr. R. Ivens, `the hill of the enclosure', owes its origin to the siting of an early monastery on an elevated hill overlooking the River Bann to the east of the present Church of Ireland in the townland of Tullylish.

That a fort, and later a monastery, should be sited here is understandable since it was a feature of early Celtic raths and monasteries that they should be situated convenient to a line of communication and close to a river. To state when the monastery at Tullylish was established is not possible but it may be presumed it was founded in the 6th. or 7th. Century.

In 1152 A.D., at the Synod of Kells, parish boundaries were established and it was after this synod that the boundaries of Tullylish and Donacloney would have been defined. Parish churches were erected to replace the old monastic settlements, which were destroyed by the piratical raids of the Vikings. Research done by the late Monsignor Christopher Murray shows that in the case of Donacloney, among the names of clergy associated with the parish in post-Norman and pre-Reformation times, is to be found an Archdeacon named Andrew who occupied that office in 1244 and who immediately afterwards became bishop of the diocese in 1244. While Archdeacon, he was in charge of Donacloney.

During the upheavals of the 1640s many churches were sacked and burned. A Cromwellian Inquisition of 1657 reported of the church at Tullylish that only the original walls remained. It was rebuilt as a Protestant church in 1698. The church in Donacloney was not destroyed in the 1641 rebellion although the Protestant clergyman resident there fled. The Church was eventually destroyed in 1689. In his Relatio Status, 1675, the Primate reported that there was a parish priest in each parish of the diocese of Dromore at that time. Curates, of course, could not be counted in view of the penal enactments then obtaining. Among priests of the diocese who were outlawed by a Williamite court held in Banbridge in 1691 was Fr. Edward Magennis from the Parish of Tullylish.