Ogham

[red solo cup]

Some examples of early Irish writing.
https://www.rte.ie/brainstorm/2020/0818/1159766-ogham-stones-ireland-inscriptions-writing-language/?fbclid=IwAR3LjDOIw7W_ydWgnl4dgoIv_QRSrztFlt9k6MMsUbRB9O700Y-BwcQJx9Y

[Prayerful]

It seems to have arisen in the late Roman era. Quite possibly Irish men had variously raided or taken service with post Roman tyrants or with Roman units in those last years. They would have seen how writing could be used and perhaps wished to do something like that for themselves.

[mikemac]

Some recently have been trying to say that the Picts were not Celts or they were not related to the Irish, Scots or Brits.  But this is contradicted with the fact that the majority of Scottish Ogham stones are located in areas which were under the control of Pictish kingdoms, along the eastern coast of Scotland north of the River Forth, and in the Orkney and Shetland islands.

The Ogham Stones of Scotland
https://www.babelstone.co.uk/Blog/2013/06/ogham-stones-of-scotland.html