Princes of East Brefney
From Irish Pedigrees; or the Origin and Stem of the Irish Nation by John O'Hart
 Arms: Vert two lions ramp. combatant or, supporting a dexter hand couped at the wrist erect and apaumée bloody ppr.
MAOLMORDHA, a younger brother of Aodh or Hugh who is No. 102 on the "O'Rourke" pedigree, was the ancestor of O'Ragheallaigh, or O'Radheollaigh; anglicised O'Rahilly, O'Reilly, O'Rielly, Rahilly, Raleigh, Reyley, Rielly, Riley, Radley, Ridley, Ryley, and Reillé.
102. Maolmordha or Myles: son of Cobthach.
103. Dubhcron: his son.
104. Cathalan: his son.
105. Ragheallach  ("ragh:" Irish, a race; "eallach," gregarious): his son; slain at the Battle of Clontarf, 1014; a quo O'Ragheallaigh.
106. Artan: his son.
107. Artgal: his son.
108. Connachtach: his son; d. 1089.
109. Macnahoidhche ("oidhche:" Irish, the night): his son; a quo Mac-na-Hoidhche, anglicised MacNight, Night, and McNeight; killed 1127.
110. Gothfrith [godfrey]: his son; killed, 1161.
111. Charles: his son; died 1196. Had a younger brother named Feargal.
112. Annadh [annay]: his son; was the last King  of East Brefney; d. 1220. Had two sons—1. Charles; 2. Fergus (also called Feargal).
113. Charles, lord of Lower Brefney: son of Annadh; was killed at the battle of Moysleaghta, A.D. 1256; had a brother named Farrell Reilly, who was the ancestor of "Clann Goffrey."
114. Donal: son of Charles: also killed at the said battle of Moysleaghta, in 1256; had a brother named Neal Caoch, who was the ancestor of Brady.
115. Giollaiosa: his son; lord of Lower Brefney; built the Abbey of Cavan; had two brothers; died in 1330.
116. Philip, lord of Lower Brefney: his son; died in 1384.
117. John, lord of Lower Brefney: his son; died in 1402.
118. Owen na Feasog, lord of Lower Brefney: his son; d. 1449. According to some genealogists this Owen na Feasog ("feasog," gen. "feasoige:" Irish, a beard) was the ancestor of Vesey and Vosey.
119. Charles, lord of Lower Brefney: his son; d. 1467.
120. John, lord of Lower Brefney: his son; d. 1510.
121. Myles, lord of Lower Brefney: his son; d. 1565.
122. Hugh Conallach, lord of Lower Brefney: his son; d. 1583.
123. John Ruadh [roe]: his son. According to some records this John, in June, in 1596, resigned the chieftaincy to his brother Philip, who died in 1601; but, according to others that brother's name was Edmond, of Kilnacrott, the last "O'Reilly" of the county Cavan, who was elected chief in 1585, and who was wounded in the wars against Queen Elizabeth; of which wounds he died in May, 1601, and was buried in the Monastery of the Franciscan Friars at Cavan. John Ruadh had a brother Mulmore (or Myles), whose Funeral Entry in Ulster's Office is dated A.D. 1636.
124. Hugh, lord of Lower Brefney: son of John Ruadh.
125. Myles: his son.
126. Colonel Edmond Buidhe [boy]: his son; resumed the title "O'Reilly;" d. in France in 1693; had a brother named Hugh, who was a Captain in France, in 1711.
127. Connell O'Reilly: his son; had a brother named Owen, who was Chief of his name; both living in France in 1711.
 O'Reilly: Of this family were (see the "O'Reilly," No. 3 pedigree) Count Alexander O'Reilly, a Spanish General, who was born at Baltrasna, in 1722; Count Andrew O'Reilly, an Austrian Field-Marshal, who was born in Ireland in 1740; the Most Rev. Edward O'Reilly, Archbishop of Armagh, who was born in Dublin in 1606; Edward O'Reilly, author of an Irish-English Dictionary, of A Chronological Account of nearly Four Hundred Irish Writers (Dublin, 1820), and other works relating to Ireland; Hugh O'Reilly, a Barrister born in the county of Cavan, who was Master in Chancery, and Clerk of the Council under James II. in Ireland, and who about 1693 published Ireland's Case Briefly Stated: or, a Summary Account of the most Remarkable Transactions of the Kingdom since the Reformation.
And of this family was the celebrated Myles "the Slasher" O'Reilly, of A.D. 1641 fame, whose son Colonel John Reilly was, according to O'Donovan, the first of the family who dropped the Irish distinctive prefix O' in connection with his name; it was, however, soon afterwards, resumed by his desendants. Colonel John Reilly resided at Clonlyn and Garryrocock, in the county Cavan, from which he was returned as Member to the Parliament held in Dublin by King James II. On the breaking out of hostilities, this John Reilly raised, at his own expense, a regiment of Dragoons, called "REILLY'S DRAGOONS," for the service of his sovereign; at the head of which, he fought at Derry, Belturbet, the Boyne, Aughrim, and Limerick. He was included in the Articles of Limerick, and so saved his property from confiscation. His regiment does not appear in Dalton's King James's Army List; but there can be no doubt of its existence, and of its having been in active service from the Siege of Derry, in 1689, till the surrender of Limerick. The only officers of that regiment, of whom we have yet read, were members of the Colonel's own family. From him descended O'Reilly, of Heath House, Queen's County; and O'Reilly, of Knock Abbey Castle, county Louth.
 Ragheallach: Some writers consider Radheolach ("radh:" Irish, a saying; "eolach," learned, skilful) as the correct spelling of this name. In this case O'Radheollaigh would be the correct Irish form of the name.
 Last King: The O'Reillys were inaugurated on the Hill of Seantoman or Shantoman, a large hill between Cavan and Ballyhaise, on the summit of which may still be seen the remains of a Druidical temple consisting of several huge stones standing upright. In after times the O'Reillys were inaugurated on the Hill of Tullymongan, above the town of Cavan; and took the tribe name of Muintir Maolmordha or the People of Maolmordha, one of their celebrated chiefs. This name Maolmordha or Mulmora was Latinized "Milesius" and anglicised "Miles" or "Myles,"—a favourite Christian name with the O'Reillys.