Eldad ben Mahli ha-Dani, English Eldad the Danite, (flourished 9th century), Jewish traveller and philologist who was generally credited with the authorship of a fanciful geographical narrative that exerted an enduring influence throughout the Middle Ages. This possibly gave rise to the legend of Prester John, the mighty Oriental priest-potentate of fabulous wealth and power.
Probably originally from southern Arabia, Eldad visited Mesopotamia, Egypt, North Africa, and Spain and caused a stir by his account of the Ten Lost Tribes of Israel. He himself claimed to be a descendant of the Danites, who, together with the tribes of Naphtali, Asher, and Gad, were said to have established a Jewish kingdom in Cush (Kush), variously interpreted as Ethiopia or, roughly, present-day Sudan. His veracity was challenged largely because the ritual prescriptions he described diverged from those of the Talmud, the rabbinical compendium of law, lore, and commentary. His Hebrew narrative, Sefer Eldad, established his reputation as a philologist whom leading medieval Jewish grammarians and lexicographers quoted as an authority on linguistic difficulties. It appeared in several languages and in widely deviating versions. The first edition was published at the Italian city of Mantua in 1480.