Fénius Farsaid (also Phoeniusa, Phenius, Féinius; Farsa, Farsaidh, many variant spellings) is a legendary king of Scythia who shows up in different versions of Irish folklore. He was the son of Boath, a son of Magog. According to some traditions, he invented the Ogham alphabet and the Gaelic language.

According to recensions M and A of the Lebor Gabála Érenn, Fénius and his son Nél journeyed to the Tower of Babel (in recension B, it is Rifath Scot son of Gomer instead). Nél, who was trained in many languages, married Scota, daughter of Pharaoh Cingris of Egypt, producing their son Goidel Glas.

In the Lebor Gabála Érenn (11th century), he is said to be one of the 72 chieftains who built Nimrod's Tower of Babel, but travelled to Scythia after the tower collapsed.

According to the Auraicept na n-Éces, 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 at Nimrod's tower. Finding that the speakers had already dispersed, Fenius sent his scholars to study them, staying at the tower, coordinating the effort. After ten years, the investigations were complete, and Fenius created in Bérla tóbaide "the selected language", taking the best of each of the confused tongues, which he calledGoídelc, Goidelic, after Goídel mac Ethéoir. He also created extensions of Goídelc, called Bérla Féne, after himself, Íarmberla, after Íar mac Nema, and others, and the Beithe-luis-nuin(the Ogham) as a perfected writing system for his languages. The names he gave to the letters were those of his 25 best scholars.

Auraicept claims that Fenius Farsaidh discovered four alphabets, the Hebrew, Greek and Latin ones, and finally the Ogham, and portrays the Ogham as the most perfected because it was discovered last.

Approximate extent of Scythia within the area of distribution of Eastern Iranian languages (shown in orange) in the 1st century BCE.^{[citation needed]}

Scythia (/ˈsiθiə/; Ancient Greek: Σκυθική) was a multinational region of Central Eurasia in the classical era, encompassing parts of Pontic steppe, Central Asia, and Eastern Europe.^{[citation needed]}

Ancient Greeks gave the name Scythia (or Great Scythia) to all the lands north-east of Europe and the northern coast of the Black Sea. According to Oxford University author's Samuel Arrowsmith, B Fellowes and Luke Graves Hansard in their 1832 book A Grammar of Ancient Geography, Scythia had two parts, Scythia Intra Imaum and Scythia Extra Imaum^[1] both covering a combined area of 1,129,000 mi² or 2,924,096 km².^[2]

The Scythians – the Greeks' name for this nomadic people – inhabited Scythia from at least the 11th century BCE to the 2nd century CE.^[3] Its location and extent varied over time but usually extended farther to the west than is indicated on the map opposite