About 2.6 million years ago some pretty large creatures roamed the planet. No, not woolly mammoths or saber-toothed tigers, we're talking about the Giant Siberian Unicorn.
More technically known as Elasmotherium, there were three species that were most recognized. The best known of the bunch was E. sibiricum, which really was the size of a mammoth. Elasmotheres also sported high-crowned molars that were constantly growing. Pretty creepy.
Much of the evidence for this creature is based on scientific theories and hypotheses. Some experts believe it trotted like a horse, while others think it lingered around like a hunched over bison. Then there are people who think it spent the majority of its life immersed in swamps like a modern-day hippopotamus.
Because they would have been herbivores, their diet would've consisted of various grasses. In many cases, these creatures likely traveled very long distances in search of grasses that were at particular growth phases.
The name "Siberian Unicorn" was coined by Johan Fischer von Waldheim in 1808, at the Natural History Museum at Moscow University. At the time, the only thing he had was a piece of the animal's lower jaw which had been donated to the museum.
Fast forward over 200 years. A nicely preserved skull was discovered in the Pavlodar region of Kazakhstan proving that the creature lived until the Pleistocene era, about 29,000 years ago, contradicting the previous belief that it had died out over 350,000 years ago.
There have also been some possible encounters with human beings. During the Middle Ages, literature began to emerge depicting run-ins with a special type of "horned beast." The Chinese would frequently write about unicorns, and although much of it was clearly symbolic in nature, there is a possibility that they encountered the real thing—especially since it's believed to have roamed the area of Eurasia.
The Shiji, or "Historical Records" of Sima Qian in the 2nd century mentions the capturing of a "deer-like" animal with one horn back in 122 BC. There's also an entry in an ancient Chinese encyclopedia of the 3rd century BC, stating that a unicorn was captured in 481 BC, but there is no drawing or painting depicting it. Meanwhile, the Arabo-Persian word for unicorn in the region was karkadann, not to be confused with Kardashian. Karkadann could mean unicorn or rhinoceros, which conveniently works out for this Siberian animal.
Although there appears to be significant historical evidence for a unicorn-like species, there is still not enough tangible evidence in the form of fossils or otherwise to legitimize these claims. It could just be that people throughout history have placed the idea of unicorns on a pedestal. Can you blame 'em?