Mide ( Meath)
Mide (“Middle”) existed as a kingdom from at least the early historic era. It included all of the modern counties of Meath, Westmeath, Longford, Offaly and south County Louth in present-day Leinster (North County Louth was considered to be part of Ulster). According to tradition, the Kingdom of Mide was created by the C2stAD Tuathal Teachtmhar.
Ptolemy’s C2nd AD map of Ireland labels the region as “Domnainn” with a capital at Rheba; this is thought to refer to the Fir Domnann, a branch of the Fir Bolg that included the ruling Uí Enechglaiss.
At the beginning of the C6th the Uí Enechglaiss were forced out of Mide by the Uí Néill / O’Neill clan, a sept of which, the Clann Cholmáin, took their place and ruled, often as Ard Rí / High Kings of Ireland, for several hundred years.
Known by the medieval era as the Ua Mael Sechlainn / O’Melaghlin dynasty, they were forced west after the late C12th Norman invasion and collapse of the kingdom.
The territory of Mide was granted by King Henry II as a Palatinate to Hugh de Lacy, who seems to have considered declaring himself king, but was murdered before he could do so. His sons Hugh and Walter angered King John, who ended their growing power by incorporating their territories into the Province of Leinster in 1210 and reducing Meath to a County.
Mag Breg, the plain of Brega, in modern County Meath, County Louth and northern County Dublin, was controlled from the mid-C6th to the mid-C8th by the Síl nÁedo Sláine branch of the southern Uí Néill. Their territory, bounded on the east by the Irish Sea and on the south by the River Liffey, extended northwards across the River Boyne and included the Hill of Tara, but only a few chieftains of Brega were also kings of Tara / Ard Rianna / High Kings of Ireland.
By the middle of the C8th the Síl nÁedo Sláine had split into two hostile branches: the Southern / Deisceart Brega of the “kingdom” of Loch Gabhair / Lagore, ruled by the Uí Chernaig; and the Northern Brega of the “kingdom” of Cnogba / Knowth, ruled by the Uí Chonaing. Despite this, several chieftains ruled over both areas, and thus Brega as a whole, until the kingdom’s extinction in the early years of the Norman invasion of Ireland.