The idea of the unicorn as a white stallion with a longhorn comes from a couple of sources. You can read the detailed breakdown of the origin of the unicorn if you interested. The three main sources for this legend are:
The Narwhal Horn
The Ancient Arthurian Legend
A Mix up with the Rhino
How the Idea of a Unicorn was Formed through Oral Storytelling
The first mention of a Unicorn was from an ancient roman called Pliny the elder. Who saw a Rhino and called it a Unicorn. Imagine trying to describe a Rhino. Pliny described the Rhino as “body of a horse, head of a stag, feet of an elephant, tail of a boar, single black horn in forehead.”
Without the benefit of a fact checking internet or a camera to snap a photo, oral storytelling was the only way to share information. Pliny’s reputation and description stood the test of time for 1600 years.
How The Rhino Became The White Horse
Further “evidence” that Unicorn are real came from the Narwhal horn. A Narwhal horn looks exactly like a unicorn horn. Imagine a Narwhal horn washing ashore as you are walking down the beach.
A Few Drinks Later
We all have that friend who likes to tells the same story over and over again. Each time the story becomes just a little bit more exaggerated. We know it’s not “true” but we laugh along with our friend.
It wouldn’t be hard to imagine how finding a “Unicorn horn” could lead to some imaginative storytelling. The finder of this unicorn horn remembers the story of a horse with a single horn. The story gets told and retold 1000 times and someone writes it down.
Ancient Arthurian Legend
One inspired medieval french writer hears this story and creates an Arthurian legend around it. The legend is the final story in the series Le Chevalier du Papegau (“The Knight of the Parrot”).
The collective idea of the white stallion with a long horn is finally fully realized.
That is how the idea of a Unicorn came from. If you want to read a bit more on the origin of the Unicorn and it’s spread through the world make sure to do so! Mentions of the unicorn are in other places across Asian but the three pieces mentioned in this article give us the best understanding of how this came into being.