Ogham ( , Modern Irish: ; , later ) is an Early Medieval alphabet used primarily to write the early Irish language (in the "orthodox" inscriptions, 4th to 6th centuries AD), and later the Old Irish language (scholastic ogham, 6th to 9th centuries). There are roughly 400 surviving orthodox inscriptions on stone monuments throughout Ireland and western Britain, the bulk of which are in southern Munster. The largest number outside Ireland are in Pembrokeshire, Wales. The vast majority of the inscriptions consist of personal names. According to the High Medieval Bríatharogam, the names of various trees can be ascribed to individual letters. For this reason, ogam is sometimes known as the Celtic tree alphabet. The etymology of the word ogam or ogham remains unclear. One possible origin is from the Irish og-úaim 'point-seam', referring to the seam made by the point of a sharp weapon. Origins It is generally thought that the earliest inscriptions in ogham date to about the 4th century AD, but James Carney believed its origin is rather within the 1st century BC. Although the use of "classical" ogham in stone inscriptions seems to have flourished in the 5th and 6th centuries around the Irish Sea, from the phonological evidence it is clear that the alphabet predates the 5th century. A period of writing on wood or other perishable material prior to the preserved monumental inscriptions needs to be assumed, sufficient for the loss of the phonemes represented by úath ("H") and straif ("Z" in the manuscript tradition, but probably "F" from "SW"), gétal (representing the velar nasal "NG" in the manuscript tradition, but etymologically probably "GW"), all of which are clearly part of the system, but unattested in inscriptions. It appears that the Ogham alphabet was modelled on another script, and some even consider it a mere cipher of its template script (Düwel 1968: points out similarity with ciphers of Germanic runes). The largest number of scholars favour the Latin alphabet as this template, although the Elder Futhark and even the Greek alphabet have their supporters. Runic origin would elegantly explain the presence of "H" and "Z" letters unused in Irish, as well as the presence of vocalic and consonantal variants "U" vs. "W", unknown to Latin writing and lost in Greek (cf. digamma). The Latin alphabet is the primary contender mainly because its influence at the required period (4th century) is most easily established, being