Tech Duinn Irish: "The House of Donn"

According to Irish folklore, the land of the dead. The origin of the name is found in the Lebor Gabala Erenn:

The wind increased on them thereupon, so that it separated from them the ship in which was Donn; and he was drowned at the Dumacha... After that Donn was buried in the Dumacha; so that from him "Tech Duin" is called, and there is his own gravemound and the gravemound of everyone who was drowned of the chieftains of his people with him, in that place.
Donn son of Mil is counted among the ancestors of the Irish, and so in this he essentially fulfils the role of "Dis Pater", from whom Caesar said the Celts claimed descent.