When did the earliest written evidence of Irish appear?

The earliest written evidence of the Irish language consists of archaic sepulchral inscriptions in ogham, an alphabetic script composed of strokes and notches incised along the edges of stone monuments. These inscriptions are generally dated to the 4th century CE, though some sources ascribe them to the 4th and 5th centuries CE.12

While there are traditions suggesting ogham was also used on wood, no material evidence of this exists. Later writings in the Latin alphabet did not appear until the 8th-century glosses in Old Irish, although some compositions from the 6th and 7th centuries have been preserved in much later manuscripts.12