In pre-Norman days their chiefs, who held high hereditary office under the Kings of Leinster, were known as Princes of Foharta (modern Forth). After the Norman invasion though their power declined they retained considerable influence.

In the sixteenth century a branch of the Nolans migrated to Connacht and became extensive landowners in Counties Mayo and Galway, in which counties the name is not uncommon to-day.

Nolan is among the forty most numerous names in the country as a whole, the great majority of persons so called being found, as might be expected, in Carlow and the adjacent counties.

In 1878, however, Connacht landlords named Nolan possessed over 12,000 acres; but there was no extensive landowner of the name in or near Co. Carlow.

There was also a small sept of O'Nuallain belonging to the Corca Laidhe group. (Possibly the Nolans of west Munster to-day stem from them). These, however, for some reason not apparent, were often called O hUllachain - thus in Lynche's De Praesulibus (1672) the two names are treated as interchangeable.

In this connexion it may be mentioned that, according to Woulfe, O hUallachain is anglicized Nolan in north Connacht. As Knowlan and Knowland this name is noted in the "census" of 1659 as numerous in Longford and in the adjacent baronies of Co. Westmeath.

In Irish the name is O Nuallain, i.e. descendant of Nuallan. The derivation of the name is obscure. the word Nuallan in modern Irish means a shout or cry, but it does not follow that the name comes from that.

In recent centuries few Nolans stand out as being particularly distinguished but several persons of the name may be mentioned. Philip Nolan (1771-1801), an Irish emigrant to America, was one of the most notorious frontiersmen and contraband traders of those early days in the West.

Most Rev. Edward Nolan (d. 1859), was Bishop of Kildare and Leighlin. and  two Nolan's had some success in the literary field, viz. Rev. Frederick Nolan (1784-1864) as a Protestant theologian and Michael Nolan (d. 1827) as a legal writer.