The etymology is from an Arabic phrase dhū-al-qarnayn meaning "two-horned", and the term was in use in medieval Latin.
In Chaucer's poem, Pandarus conflates it with the Pons asinorum, an earlier result in Euclid on the isosceles triangle.
[5] John Selden made the connection to dū'lkarnayn, a Persian term via Arabic, writing in his 1612 preface to Michael Drayton's Polyolbion.
[6][7] Stephen Skinner in the later 17th century corrected a muddled annotation to Chaucer's line by Thomas Speght.
[9] In consequence, it is to the word's derived Eastern associations that Henry Milner Rideout points in the title of his 1926 Dulcarnon: A Novel, described as "one of his best adventures in the fairyland of the Orient".