The Kingdom of Osraige was one of the ancient Kingdoms of Ireland. The Kings of Osraige, the Mac Giolla Phádraig family, reigned over Osraige and Cill Chainnigh was their stronghold. The Kingdom of Ossory existed from at least the 2nd century until the 13th century AD. The current ecclesiastical dioceses of that area is still known as Ossory. The medieval Diocese of Ossory and was established in 549 AD, and its territory corresponded to the medieval Kingdom of Ossory. In historic times, Kilkenny replaced Aghaboe as the chief church in Osraige.

The kingdom was bounded by two of the Three Sisters the rivers Barrow and Suir and the northern limit was, generally, the Slieve Bloom Mountains. The Osraige —their name means people of the deer— inhabited much of modern County Kilkenny and parts of neighbouring County Laois. To the west and south, Osraige was bounded by the River Suir, to the east the watershed of the River Barrow marked the boundary with Leinster, and to the north it extended into and beyond the Slieve Bloom Mountains. The River Nore ran through the Kingdom.

Osraige formed the easternmost part of the kingdom and province of Munster until the middle of the 9th century, after which it was attached to Leinster. Osraige was largely a buffer state between Leinster and Munster. Its most significant neighbours were the Loígsi, Uí Cheinnselaig and Uí Baircche of Leinster to the north and east and the Déisi Muman, Eóganacht Chaisil and Éile of Munster to the south and west.

The name Osraige is said to be from the Usdaie, a Celtic tribe that Ptolemy's map of Ireland places in roughly the same area that Osraige would later occupy. The territory indicated by Ptolemy probably included the major late Iron Age hill-fort at Freestone Hill which produced some Roman finds. Also the interesting burial at Stoneyford which is of typical Roman type and probably dates to the 1st century AD.[43] The Osraighe themselves claimed to be descended from the Érainn people. Others propose that the Ivernic groups included the Osraige of the Kingdom of Osraige/Ossory.[44] The Brigantes were the only Celtic tribe to have a presence in both England and Ireland, in the latter of which they could be found around Kilkenny, Wexford and Waterford.

Pope Adrian IV gave Norman King Henry II of England permission to claim Ireland 1154. The Cisternians came to Jerpoint and Kilkenny around 1155/60. Jerpoint Abbey is founded by Donal MacGiollaPhadruig, King of Ossory 1158. In 1168, Dermot MacMurrough the King of Leinster was driven out of his kingdom by Rory O'Connor the High King of Ireland with the help of Tiernan O'Rourke. MacMurrough looked for help from Henry II and got help from a Cambro-Norman lord notable Richard de Clare, 2nd Earl of Pembroke, known to history as Strongbow. MacMurrough secured the services of Richard, promising him the hand of his daughter Aoife of Leinster and the succession to Leinster. Richard and other Marcher barons and knights by King Henry assembled an army. The army, under Raymond le Gros, took Wexford, Waterford and Dublin in 1169 and 1170, and Strongbow joined them in August 1170. The day after the capture of Waterford, he married MacMorrough's daughter, Aoife.

The Lordship of Ireland was a lordship created in the wake of the Norman invasion of Ireland in 1169–71. Kilkenny formed part of the lordship of Leinster. Strongbow became Lord of Leinster in 1171.The Kilkenny Castle (Irish: Caisleán Chill Chainnigh) was built in 1195 to control a fording-point of the River Nore and the junction of several routeways. It was a symbol of Norman occupation and in its original thirteenth-century condition it would have formed an important element of the defences of the town with four large circular corner towers and a massive ditch, part of which can still be seen today on the Parade. (Wikipedia - County Kilkenny)