More on Celtic Ogham (Tree Alphabet)“R Graves proposed that the ogham alphabet encoded a set of beliefs originating in the Middle East in Stone Age times, concerning the ceremonies surrounding the worship of the Moon goddess in her various forms. Graves' argument is extremely complex, but in essence he argues that the Hebrews, Greeks and Celts were all influenced by a people originating in the Aegean, called 'the people of the sea' by the Egyptians, who spread out around Europe in the 2nd millennium BC, taking their religious beliefs with them.” - Graves, R 'The White Goddess', pp. 61, 123, 1961 - https://en.wikipedia.org/wiki/Ogham#cite\_note-34
See https://thecelticjourney.wordpress.com/tag/celtic-tree-alphabet/ for more on Ogham.