"Beith" corresponds to the letter "B" in the Ogham alphabet.
The Ogham alphabet is thought to be named after the Irish god Ogma. One theory of its origins is that it evolved out of a system of tallies used for accounting. Ogham is also known as or ogham craobh, beth luis fearn or beth luis nion.
About 500 Ogham inscriptions have been found in Ireland, Scotland, Wales, England and the Isle of Man dating from between the 4th and 7th centuries AD. There are inscriptions in ancient Irish and Pictish which have not been deciphered. A number of bilingual inscriptions in Ogham and Latin or Ogham and Old Norse written with the Runic alphabet have been found.
While all surviving traces of Ogham are inscriptions on stone, it was probably more commonly inscribed on sticks, stakes and trees. Inscriptions generally take the form of somebody's name and the name of a place and were probably used to mark boundaries.
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