“MANE, (of horse &c) Dut. Maene Ger. Maene Sw. Maan. Minshew derives – because it flows from his neck. Wachter from Lat. (of the Lower Ages) Minare to lead, to guide, because the horse was guided by means it before the bridle was invented. Junius the Gr. Mavvos or uavos a kind of adapted to the neck. Kilian says that it is so from its resemblance to the moon, whence it called by Martial juba lunata, and by Catullus rutila. May it not be from A.S. Magen, magn, main strength?”
Excerpted from “A New Dictionary of the English Language, Volume 2,” by Charles Richardson, 1855. I love this poor dead scholar for for his literary eyeroll at so many false cognates.
Like most of our baser equestrian words, ‘mane’ does come from the Anglo-Saxon, though I am inclined to believe it is from gemáne, for maned. Curious, though, is this idea that somewhere in the mists of time, people dared to get on an unbroke horse without even the benefit of the headgear used for the previously domesticated sheep, goats, or cattle (and possibly even donkeys)!