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The modern English name came from the Viking settlement of Dyflin, which derived its name from the Irish Duiblinn. The Celtic settlement's name is still used as the Irish name of the modern city, though the first written evidence of it is found in the Annals of Ulster of 1368. The Viking settlement of about 841 was known as Dyflin, from the Irish Duiblinn (or "Black Pool", referring to a dark tidal pool where the River Poddle entered the Liffey on the site of the Castle Gardens at the rear of Dublin Castle), and a Gaelic settlement, Áth Cliath ("ford of hurdles") was further upriver, at the present day Father Mathew Bridge at the bottom of Church Street. Beginning in the 9th and 10th centuries, there were two settlements where the modern city stands.
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It is now thought that the Viking settlement was preceded by a Christian ecclesiastical settlement known as Duiblinn, from which Dyflin took its name. Recently, however, doubt has been cast on the identification of Eblana with Dublin, and the similarity of the two names is now thought to be coincidental. This would seem to give Dublin a just claim to nearly two thousand years of antiquity, as the settlement must have existed a considerable time before Ptolemy became aware of it. The earliest reference to Dublin is sometimes said to be found in the writings of Claudius Ptolemaeus (Ptolemy), the Egyptian-Greek astronomer and cartographer, around the year 140, who refers to a settlement called Eblana.
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