The name Dublin comes from the Gaelic dubh linn or “black pool” - where the Poddle stream met the River Liffey to form a deep pool at Dublin Castle. The city's modern name - Baile Áth Cliath – means the “town of the ford of the hurdles”. Ireland's four principal routeways converged at a crossing place made of hurdles of interwoven saplings straddling the low-tide Liffey.
837 AD – 917 AD: In 837, sixty Viking longships attacked churches round the Poddle and Liffey estuary, and the invaders made a permanent settlement in 841. 917 – 1014: Dublin was the Viking world’s largest city and traded from Iceland to Constantinople. The first genuine ruler of all Ireland - High King, Brian Boru - was rebelled against by Dublin Vikings and the Leinster Irish. With the aid of Vikings, Brian crushed his foes, then was himself slain, in an epic battle atClontarf in 1014. 1014 – 1170: The Vikings adopted Christianity and founded Christ Church Cathedral. In 1169, the deposed Irish King MacMurrough sought help from south-west Wales Normans who, under their leader Richard FitzGilbert de Clare (Strongbow), seized Dublin.