Trapped between this land bridge and the ice sheet to the north, the Irish Sea is filled by melt water that forms a vast lake.At this time, the land bridge is finally submerged beneath the salt water of the Atlantic Sea.
The first written record of contact with 'Albion' (by a Greek writer) names both Britain/Alba and Ireland as the 'Prettanik' islands.
This is the oldest known name, which then leaves them to be distinguished from each other by Alba (meaning 'white', probably named after the chalk cliffs of Dover), and Hibernia, which is the rather sloppy Latin translation of 'Ierne' as written by the Greeks.
Then in the late fourth century, Niall of the Nine Hostages apparently dominated much of Ireland.
His offspring, the U Neill, used a descent system to describe themselves, and this appears to have been adopted by most of the island.
One of those captured slaves helped to convert the Irish to Christianity - the Romano-British Saint Patrick in the mid-fifth century AD.
Thanks to that, and isolated from the chaos that swept Britain during the Anglo-Saxon invasion, Ireland was able to develop its own rich and prominent Christian culture.
The earliest priest-kings who claimed the high kingship are often legendary, with little or no proof of their actual existence bar oral history.
As such, and where necessary, they are shown below with a lilac-tinted background.
During the sixth century, Saint Columba followed in the footsteps of the earlier Irish raiders to spread the Celtic Church into Dl Riata (now western Scotland), while in western Wales the Disi settled and helped to form the kingdom of Dyfed.
Ireland was never politically united enough to translate its religious and cultural influence into political power.
Ierne is fairly obviously a mispronunciation of 'Er Inis' or 'Eire Innis' (various spellings are available), meaning 'West Island' in common Celtic. The name remains in use today in its full form - Eireann.