Celestine I in AD 431. A variation is that the alphabet was first invented, for whatever reason, in 4th-century Irish settlements in west Wales after contact and intermarriage with Romanised Britons with knowledge of the Latin alphabet. In fact, several ogham stones in Wales are bilingual, containing both Irish and British Latin, testifying to the international contacts that led to the existence of some of these stones. A third theory put forward by the noted ogham scholar R. A. S. Macalister was influential at one time, but finds little favour with scholars today. Macalister believed that ogham was first invented in Cisalpine Gaul around 600 BC by Gaulish druids as a secret system of hand signals, and was inspired by a form of the Greek alphabet current in Northern Italy at the time. According to this theory, the alphabet was transmitted in oral form or on wood only, until it was finally put into a written form on stone inscriptions in early Christian Ireland. Later scholars are largely united in rejecting this theory, however, primarily because a detailed study of the letters shows that they were created specifically for the Primitive Irish of the early centuries AD. The supposed links with the form of the Greek alphabet that Macalister proposed can also be disproved. Macalister's theory of hand or finger signals as a source for ogham is a reflection of the fact that the signary consists of four groups of five letters, with a sequence of strokes from one to five. A theory popular among modern scholars is that the forms of the letters derive from the various numerical tally-mark systems in existence at the time. This theory was first suggested by the scholars Rudolf Thurneysen and Joseph Vendryes, who proposed that the ogham script was inspired by a pre-existing system of counting based around the numbers five and twenty, which was then adapted to an alphabet form by the first oghamists. Legendary accounts According to the 11th-century Lebor Gabála Érenn, the 14th-century Auraicept na n-Éces, and other Medieval Irish folklore, ogham was first invented soon after the fall of the Tower of Babel, along with the Gaelic language, by the legendary Scythian king, Fenius Farsa. According to the Auraicept, Fenius journeyed from Scythia together with Goídel mac Ethéoir, Íar mac Nema and a retinue of 72 scholars. They came to the plain of Shinar to study the confused languages