Leinster holds the current counties of Louth, Longford, Dublin, Kildare, Offaly, Laois, Wicklow, Kilkenny, Carlow and Wexford. Much of this province can be characterized as rolling hills and farmland. Though there are some mountains in the southeast, much of the area is relatively flat. With the fertile soil and an abundance of water, Leinster is well suited to agriculture. Farming and the raising of cattle and fine horses were the main occupations of the early inhabitants.

The province also boasts one of the largest coals fields in Ireland, as well as substantial deposits of copper, lead, iron and pyrites. Granite and slate are also quarried. There are extensive peat fields near the Bog of Allen in the northern part of the province. Fishing is an important industry in much of the province. Catches include salmon, cod, haddock, sole, plaice and oysters. Leinster shares the legendary fame of Fionn Mac Cumhaill and the Fianna. The Hill of Allen, Dun Ailinne, is said to be the site where Fionn and his band of warriors camped. Dublin (Dubh Linn) and Wexford were two of the earliest Viking settlements in Ireland. Brian Boru broke the powere of the Vikings at the Battle of Clontarf in 1014, but paid for the victory with his life.


There are 4 important "cities" of ancient Leinster.

Dún Ailinne in Kildare, located on the hill of Knockaulin, was one of the most important royal sites in S. Leinster. It is the largest hillfort in Ireland. However, there is little evidence for occupation, which indicates that it must have been a center for seasonal assemblies and activities. Excavations at the site uncovered artifacts ranging from Neolithic to Iron Age but nothing to show domestic or residential activity. The original entrance was on the east and a road led up to the main structure contained in the palisade. A ditch encloses the 34 acres of the site but this ditch was probably not for defensive purposes because it was dug inside the bank. From its spacious area and highly significant hilltop position, as well as the vast amounts of time and effort put into building Dun Ailinne, we know it was a place of very important ritual assemblies. The mythical Leinster king, Find File, is thought to have lived there. Until the 7th century it was the most important royal site in south Leinster.

Dún Naas In annuals and records the name of Naas appears in three forms: An Nás, meaning "The Place of Assembly;" Nas Laighean meaning "The Place of The Leinstermen;" and Nás na Riogh meaning "The Place of Assembly of the Kings." The original Dún of Naas destroyed by King Tuathaill Teachtmhar in 134 AD was rebuilt by Luighdech Eithlenn, King of Leinster in 140 AD. It was burned down by Cormac Mac Airt, High King of Ireland in 277 AD to avenge the massacre of thirty royal maidens and a large number of their attendants by the Leinster king, Dunlang. According to the Dindsenchas, it was rebuilt once more by the legendary Princess Tailtinn. The "Four Masters" tells that in 705 Conall Cinn Maghair, son of Fergus of Fanat, led an army into Leinster, devastated Naas, carrying away hostages, and tribute. He composed a poetic farewell to the Liffey, in which he praises the unbroken level grass-producing surface of its plain, as far as the Dun of Naas . The "Annals of Ulster" mention its ruin quoting the ancient poem by Conall, which implies that the royal residence was a large single-roofed house on the Dún. "Thou wert safe, except thy roof, O Dún of Naas. The plain of Liffey ... today it is a scorched place."

Dun Naas consists of two "motes" (earthwork mounds), North and South. The North mote is ten meters high with a diameter of almost a hundred meters at the base. This was constructed during the Viking era on the site of the original Dun. The south mote is now reduced to just a low hill and shows no evidence of fortifications.

Croghan Hill/Cruachain Bri Eile Located ten miles northeast of Tullamore in north County Offaly, Croghan Hill, almost circular and 4000 feet in diameter, rises high above the vast surrounding bog. It is actually the remnants of the main vent of an ancient volcano. People lived in this area since Mesolithic times, 9,000 years ago. During the neolithic age (circa 2,000 BC) the first burials were made there and a cairn was erected, obviously for an important person judging by the amount of work and workers necessary. Near this cairn, a hillfort was constructed sometime between the Bronze and early Iron Age, probably a defensive and/or assembly place that might have even served as a kind of urban center for ritual gatherings as well as a marketplace. The strategically significant site of Croghan Hill, overlooking the surrounding bog, kept the people of Leinster safe from their enemies, the Ui Neill dynasty of Mide. Nevertheless, in the year 365 there was a battle between the "king of Tara" Eochaidh Muighmheadhon, and Eanna, King of Leinster at Croghan Hill.

Dinn Rig was a citadel located on the west bank of the Barrow River near Leighlinbridge, County Carlow. There are many references to this site in early Irish literature, usually named as the fortress of south Leinster kings. Legend says that the Fir Bolg king Slaine is buried there. In another story "The Destruction of Dind Rig" the citadel is burned to the ground by Labraid Loingsech.