The Legend Beasts are ancient creatures of Chima who chose not to drink the Chi water and evolve, thus leaving them pure. They have an implied connection to Mount Cavora and were the only creatures who could restart the Chi falls after they were stopped by the Spiders and the Black Cloud.
Coming into existence countless eons ago, the Skunk Legend Beasts would use the gasses emitted under the light of the Hundred Year Moon to bring life and nourishment to the barren land that would become Chima, thus making it hospitable to countless other forms of life. As a result, the now flourishing world of Chima would be populated by various species of Legend Beasts. Later, four Hunter Tribes would evolve from the Saber-Tooth, Vulture, Mammoth, and Ice Bear Legend Beasts respectively.
It was the first one to be found, trapped by the Outland Tribes in Episode 20, For Chima!
Clever and resourceful, the Eagle Legend beast was the fifth beast freed, though technically, she was never trapped, as the Scorpions stole her eggs and left them in a trap with the Bear Legend. In the webisode "Eggs-termination" at the end of the webisode, the eggs start to glow. This could be interpreted as the eggs starting to hatch, or an unknown Legend Beast related event.
Rhino Legend Beast
Beaver Legend Beast
Skunk Legend Beast
According to ancient legends, the Skunk Legend Beasts were responsible for turning Chima from its once-desolate state to a lush jungle, as the gasses emitted by them during the Hundred Year Moon would cause flora and life to flourish immensely. Later, after the imperfect Great Illumination rained Chi waters on the land, all the Skunk Legend Beasts presumably drank it and were transformed, thus leaving no Beasts behind.
Bat Legend Beast
Saber-Tooth Legend Beast
A mythical Legend Beast from Sabre-Tooth lore, the Saber-Tooth Beast is the only of its kind to not have evolved. According to myth, it came across Sir Fangar, who made a vow to bring his tribe to glory. In order to seal his vow, the Saber-Tooth Beast bestowed one of its massive fangs to Fangar, who would help honor his promise by forging the tooth into his personal weapon Glacior. Later, the Saber-Tooth lost its other fang in an unknown incident, prompting Fangar to set a massive bounty on the missing relic.