I Pictish symbol stone with an ogham inscription. The etymology of the word "ogam" or "ogham" remains unclear. A variety of crosses bear inscriptions in ogham, an early medieval Irish alphabet. There are many megalithic tombs and ogham stones in the county. Primitive Irish is first attested in Ogham inscriptions from the 4th century AD. There was considerable Irish colonisation in Dyfed, where there are many stones with ogham inscriptions. Unlike orthodox ogham, some medieval inscriptions feature all five Forfeda. On the inner lintel is an ogham inscription. Jackson was content to write off Ogham inscriptions as inherently unintelligible. Inscription in the ogham alphabet began in the 4th century. Ogham stones are found throughout County Kilkenny. Their influence is evident in a change of language in Ogham inscriptions on Man. This is evident in the change in language used in Ogham inscriptions. Even the Younger Futhark are introduced as a kind of "Viking ogham" (nrs. 91, 92). Before that time a simple writing system known as "ogham" was used for inscriptions.