The kings of Leinster ruled from the establishment of Leinster during the Irish Iron Age until the 17th century Early Modern Ireland. According to Gaelic traditional history found in works such as the Book of Invasions, Leinster was created during the division of Ireland among the Irish Gaels, descendants of Milesius: Leinster was one of the territories held by the offspring of Heremon. In the 7th century BC, the branch of the Heremonians who would establish Leinster, starting with Úgaine Mór, were also High Kings of Ireland and Kings of Tara. Their ascent to hegemony in Ireland was associated with the decline in influence of their Ulster-based Heremonian kinsmen from the Érainn. Apart from Úgaine Mór, other prominent Kings of Leinster from this period who were also High Kings of Ireland were Labraid Loingsech and Cathair Mór. A mythology developed that Labraid Loingsech had horses ears: he spent some time exiled in Transalpine Gaul (dated roughly to the period of the Roman–Gallic wars) where his grandmother was from and returned to Ireland with Gaullish mercenaries. He established a base in the area, which was renamed from "Gailian" to Leinster, in reference to the pointed-spears held by the Gaullish Gaesatae mercenaries who provided the backbone of Labraid Loingsech's powerbase and brought him to the High Kingship. Cathair Mór, who was also a High King of Ireland, is perhaps the most important figure genealogically in Leinster as all of the subsequent kinship groups which ruled Gaelic Leinster claimed descent and legitimacy to rule from one of his ten sons who had offspring. By the time of Early Christian Ireland, the Laighín had lost their grip on Irish hegemony with the rise of the descendants of Conn of the Hundred Battles (the Connachta and the Uí Néill). The latter pushed down into Leinster and created the Kingdom of Meath based at Uisnech, under the Southern Uí Néill from territories belonging to the Kingdom of Leinster and to the west Osraige was taken from the Laighín by the Corcu Loígde of Munster. During the 5th to the early 8th centuries, the Kingship of Leinster was contested by various different branches of the Laighín, including the Uí Cheinnselaig (ancestors of the Mac Murchada and Caomhánach), the Uí Dúnlainge (ancestors of the O'Byrnes and the O'Tooles), the Uí Bairrche (ancestors of the Mac Gormáin), the Uí Máil (ancestors of the Ó Conchobhair Uí Failghe) and others. From the 8th until the 11th century, the kingship of Leinster rotated in a remarkably stable arrangement between three branches of the North Leinster Uí Dúnlainge kinship, namelt the Uí Fáeláin (ancestors of the O'Byrnes), the Uí Muiredaig (ancestors of the O'Tooles) and the Uí Dúnchada (whose descendants became the MacGillaMoCholmóc and later the FitzDermots). In the 9th century, the Laighín also regained control of Osraige but it remained a largely independent realm under the Mac Giolla Phádrag, from the semi-autonomous Uí Failghe kinship group. The Uí Cheinnselaig in South Leinster took back control of the kingship of Leinster in the 11th century, with Diarmait mac Máel na mBó, who became the first Leinsterman to be High King of Ireland in over a thousand years and claimed to the most senior line of the Laighín. An enemy of the Vikings of Dublin, he gave refuge to the sons of Harold Godwinson after the Normans conquered England. It is from this line that the Mac Murchada family originate and later Diarmait Mac Murchada would be implicated in the 12th century Norman invasion of Ireland after he tried to win back his Leinster throne. The reigning dynasty adopted the surname Caomhánach (Kavanagh) and continued to rule a rump Kingdom of Leinster until the early 17th century, with the last recorded King of Leinster being Domhnall Spáinneach Mac Murchadha Caomhánach. Throughout the centuries after the Norman invasion, several Kings and also leaders from dynasties who had previously held the Kingship of Leinster, continued to resist the invasion and hounded the English Pale periodically from the Wicklow Mountains: including the leaders of the O'Toole and O'Byrne clans (notable examples include Art Óg Mac Murchadha Caomhánach and Fiach McHugh O'Byrne) until the 17th century.

Legendary Kings

Kings of Leinster

Laigin, classical antiquity

634–594 BC 594–592 BC 592–592 BC 592–542 BC 542–523 BC 119–122 AD

Uí Cheinnselaig, 5th century

– –436 –

Uí Bairrche, 5th century

– (claimant) || || Son of Dáire Barrach mac Cathair Mór ||unknown || unknown – (claimant) || || Son of Muiredach Mo Sníthech mac Dáire Barrach ||unknown || unknown

Uí Enechglaiss, –446

–446

Uí Cheinnselaig, 446–483

446–483

Uí Garrchon, 483–495

483–485 485–495

Uí Dúnlainge, 495–592

495–527 527–535 535–546 546–576 576–592

Uí Máil, 592–595

592–595

Uí Cheinnselaig, 595–624

595–605 605–624

Uí Máil, 624–633

624–633

Uí Dúnlainge, 633–666

633–656 656–666

Uí Cheinnselaig, 656

656

Uí Máil, 666–680

666–680

Uí Dúnlainge, 680–693

680–693

Uí Máil, 693–715

693–715

Uí Dúnlainge, 715–728

715–727 727–728

Uí Fáeláin (Uí Dúnlainge), 728–738

728–738

Uí Dúnlainge, 738

738

Uí Cheinnselaig, 738

738

Uí Muiredaig (Uí Dúnlainge), 738–760

738–760

Uí Dúnchada (Uí Dúnlainge), 760–776

760–776

Uí Fáeláin (Uí Dúnlainge), 776–785

776–785

Uí Muiredaig (Uí Dúnlainge), 785–795

785–795

Uí Dúnchada (Uí Dúnlainge), 795–808

795–808

Uí Muiredaig (Uí Dúnlainge), 808–818

808–818

Uí Fáeláin (Uí Dúnlainge), 818–829

818–829

Uí Muiredaig (Uí Dúnlainge), 829–834

829–834

Uí Dúnchada (Uí Dúnlainge), 834–838

834–838

Uí Muiredaig (Uí Dúnlainge), 838–854

838–851 851–854

Uí Dúnchada (Uí Dúnlainge), 854–862

854–862

Uí Fáeláin (Uí Dúnlainge), 862–863

862–863

Uí Muiredaig (Uí Dúnlainge), 863–871

863–869 869–871

Uí Fáeláin (Uí Dúnlainge), 871–884

871–884

Uí Dúnchada (Uí Dúnlainge), 884–885

884–885

Uí Fáeláin (Uí Dúnlainge), 885–909

885–909

Uí Muiredaig (Uí Dúnlainge), 909–917

909–917

Uí Dúnchada (Uí Dúnlainge), 917–943

917–942 942–943

Uí Fáeláin (Uí Dúnlainge), 943–947

943–947

Uí Muiredaig (Uí Dúnlainge), 947–958

947–958

Uí Dúnchada (Uí Dúnlainge), 958–966

958–966

Uí Fáeláin (Uí Dúnlainge), 966–972

966–972

Uí Muiredaig (Uí Dúnlainge), 972–978

972–978

Uí Dúnchada (Uí Dúnlainge), 978–1003

978–984 984–1003

Uí Fáeláin (Uí Dúnlainge), 1003–1014

1003–1014

Uí Muiredaig (Uí Dúnlainge), 1014–1016

1014 1014–1016

Uí Fáeláin (Uí Dúnlainge), 1016–1018

1016–1018

Uí Muiredaig (Uí Dúnlainge), 1018–1033

1018–1024 1024–1033

Mac Giolla Phádraig (Dál Birn), 1033–1039

1033–1039

Uí Muiredaig (Uí Dúnlainge), 1039–1042

1039–1042

Mac Murchada (Uí Cheinnselaig), 1042–1115

1042–1072 1052–1070 1072–1075 1075–1089 1089–1092 1092–1098 1098–1115

Ó Conchobhair Uí Failghe, 1115

1115

Mac Murchada (Uí Cheinnselaig), 1115–1171

1115–1117 1117–1126 1126–1166 1169–1171

Caomhánach, 1171–1603 (Uí Cheinnselaig)

1171–1175 – –1282 1282–1314 1314–1323 1323–1338 1338–1347 1347–1354 1354–1362 1362–1369 1369–1375 1369–1375 1375–1417 1417–1478 1478 1478–1512 1512–1517 1517–1523 1523–1531 1531–1547 1523–1531 1531–1557 1557–1582 1582–1603