Following the political partition of Ireland into separate national states, the Republic of Ireland ( originally the Irish Free State then Éire ) and Northern Ireland ( a political division of the United Kingdom ), the then Committee of the Irish Rugby Football Union decided that it would continue to administer its affairs on the basis of the full 32 Irish counties and the traditional four provinces of Ireland: Leinster ( 12 counties ), Ulster ( 9 counties ), Munster ( 6 counties ), and Connacht ( 5 counties ).

The areas under the control of these kings were: Ulster (), Leinster (), Connacht (), Munster () and Mide ().

Bruce's Irish ancestors included Eva of Leinster ( d. 1188 ), whose ancestors included Brian Boru of Munster and the kings of Leinster.

With the kings of Ulster and Leinster, he marched north to Mag nAi and forced Conn to make a treaty with him, diving Ireland between them: Conn controlling the north, or Leth Cuinn (" Conn's half "), and Mug Nuadat the south, or Leth Moga (" Mug's half "), with the border lying between Galway in the west and Dublin in the east.

After fifteen years of peace Mug Nuadat broke the treaty and declared war, along with the kings of Ulster and Leinster.

In his account Mug Nuadat obtains an army from the king of Leinster and expels the kings of Munster, here Lugaid Allathach, Dáire Dornmhor and Aonghus.

For about three hundred years it was a Viking town, a city state, largely independent and owing only token dues to the Irish kings of Leinster.

The town became the capital of the Kingdom of Leinster when the kings of that southern part of the province established their seat of power there.

The Irish language name for Naas, Nás na Ríogh literally means Meeting Place of the Kings, as the place historically hosted meetings of pre-Norman Irish kings from the Kingdom of Leinster.

* O ' Byrne, Emmett ( 2003 ) War, Politics and the Irish of Leinster Dublin: Four Courts ; " The MacMurrough-Kavanagh kings of Leinster ; Outline Genealogies I, Ia, Ib ", pages 247-249.

In the 8th century there was a battle between rival kings near the church of St. Coca, then in the territory of Carbury and close to the border between Leinster and Meath.

Dinnshenchas Érenn, probably composed by Cináed Ua Hartacáin ( d. 975 ), also selected the nearby Cnoch Liamhna for mention as one of the “ assemblies and noted places in Ireland ”, an indication of the strength of the local ruling family, the Uí Dúnchada branch of the Uí Dúnlainge who supplied ten kings of Leinster from their base on nearby Lyons Hill between 750 and 1050.

Castledillon, situated on the south bank of the River Liffey opposite Straffan, is an ancient monastic site in its own right founded by Iollathan of the desert ( feast day is listed as 2nd Feb in the Martyrology of Tallaght ) and accorded a genealogy which indicated close kinship with the Ui Dunglainge kings of Leinster.

The oldest source for Túathal's story, a 9th century poem by Mael Mura of Othain, says that his father, Fíacha Finnolach, was overthrown by the four provincial kings, Elim mac Conrach of Ulster, Sanb ( son of Cet mac Mágach ) of Connacht, Foirbre of Munster and Eochaid Ainchenn of Leinster, and that it was Elim who took the High Kingship.

However by the time of his son's birth Muirchertach was subordinate to the new kings of Leinster, the Uí Cheinnselaig.

In 1166, Lawrence's brother-in-law Diarmait was deposed as King of Leinster by an alliance of Irish kings and princes, led by High King Ruaidri Ua Conchobair and King Tigernan Ua Ruairc of Breifne.

The last of Diarmait's ancestors to have been counter as king of all Leinster was Crimthann mac Énnai, whose death is placed in the late 5th century, but his ancestors, most recently his great-grandfather Domnall mac Cellaig ( died 974 ), had been counted among the kings of the Uí Cheinnselaig.

The rival Uí Dúnlainge, based in northern Leinster around Naas and Kildare, who also enjoyed the support of the powerful Clann Cholmáin kings of Mide, dominated Leinster until the time of Brian Bóruma.

They are placed in the prehistoric past, in the time of Túathal Techtmar, who imposes the tribute of 5000, in other accounts 15000, cattle on the kings of Leinster as the honour price — known as éraic in early Irish law codes — for the death of his daughters.

In the mid 11th century, the Kingdom of Leinster began exerting influence over Dublin, but its kings remained Norse-Gaels until the Norman invasion of 1171.

According to her biographers her parents were Dubhthach, a Pagan chieftain of Leinster, and Brocca, a Christian Pict and slave who had been baptised by Saint Patrick.

Among the Cruthnian tribes that survived into the Christian era the most prominent were the Dál nAraidi in Ulster, and the Loíges and Fothairt in Leinster.

The main building has undergone regular extensions from Victorian times, through to a major extension to create offices for TDs in the 1960s, to most recently the building of Leinster House 2000, a new block of offices built to the north of the original ducal palace.

Toulouse have won the competition a record four times, Leinster three times, while Munster, Leicester Tigers and London Wasps have won it twice each.

He coached Leinster to Interprovincial Championship success five times between 1979 and 1983 before he succeeded Willie John McBride as Ireland coach during the 1984-85 season.

The intimate nature of the conflict meant that the rebellion at times took on the worst characteristics of a civil war, especially in Leinster.

Only Blackrock College ( 66 ) have won the Leinster Senior Cup more times than Belvedere ( 10 ).

Since then, Ulster has been arguably the most successful of the four Irish provinces ( the others are Connacht, Leinster and Munster ) having won the Inter-Provincial Championship a record 26 times as well as being the first Irish side to win the European Cup, which they won back in 1999 against French side US Colomiers at Lansdowne Road in Dublin.

Leinster have twice been PRO12 champions and three times champions of Europe.

The modern western province of Connacht ( Irish Cúige Chonnacht, province, literally " fifth ", of the Connachta ) takes its name from them, although the territories of the Connachta also included at various times parts of southern and western Ulster and northern Leinster.

In late prehistoric times, beginning in the fifth century, the ancestors of the Uí Néill — descendants of Niall of the Nine Hostages — expanded into the east midlands of Ireland, southern Ulster and northern Leinster, at the expense of the previous overlords.

The principal sport in the college is rugby, with Blackrock having held the Leinster Schools Senior Cup 66 times.

It has also won the Leinster Schools Junior Cup 46 times.

The college competes in Leinster Senior Schools having won the senior relay cup multiple times, most recently in 2008, and the Irish senior schools, regularly making finals.

The school has a strong rugby playing tradition, having won the Leinster Schools Junior Cup three times: in 1991, 2002 and 2012 in addition to reaching 6 JCT finals in a row up to 2012.

He has played professional rugby for many seasons having played with Leinster ( 2000 – 2003 ), Harlequins ( UK )( playing 133 times between 2003 – 2009 ) and re-signing for Leinster in 2009 & 2010.

In 831 and 832, he is recorded as taking an army of Leinster and Munster into East Meath, plundering as far north as Slane, while also raiding the Dealbhna Beatha of southern Offaly three times, and burning Clonmacnoise.

The modern name of this province, Leinster ( Irish: Laighin ), preserves the memory of this Laginian conquest, although in ancient times it was much smaller than the modern province.

* Kings, the kingship of Leinster, and the regnal poems of " laidshenchas Laigen ": a reflection of dynastic politics in Leinster, 650-1150, Edel Bhreathnach, Seanchas ...", pp. 299 – 312.

* Cecile O ' Rahilly ( ed & trans ), Táin Bó Cúalnge from the Book of Leinster, Dublin Institute for Advanced Studies, 1967, pp. 234-239

* Cecile O ' Rahilly ( ed & trans ), Táin Bó Cúalnge from the Book of Leinster, Dublin Institute for Advanced Studies, 1967, pp. 138-141