The origin of the Thunderbird goes back to the Mississippian culture of the Mound Builders of North America that were major elements of the Southeastern Ceremonial Complex of American prehistory. Legend says that the enemy of the Thunderbird of some sea monster that was believed to have belonged from the underworld and was a sea panther. The basic representation of the sign of the Thunderbird was linked to being an omen of war which was heard with the sound of thunder.
The name of the Thunderbird was originated from the belief of Native Americans of a mighty bird causing the loud sound of thunder due to the movement of its mighty wings which also stir the wind. The Native American people also had the belief that lightning was caused due to the ability of the Thunderbird to shoot lightning from its eyes. A previously mentioned, thunder was an omen of war, to them, thunder meant that the angels and spirits in the skies beyond are at war. But this was not linked to the war in skies only but was also believed that it foretold the victory of the wars being held at the ground as well.
It is a mythical creature and is one of the most dominant icons present in the Native American culture and art. Description of the Thunderbird is found throughout the Native American culture in cave art, totems and pottery. There are also multiple legends and myths liked to this mystical creature. In one of the legends it was believed that if you see a bird in your dream, you are destined to become a Medicine man, but on the other hand, if you particularly saw a Thunderbird in your dream that means that it is your destiny to become a sacred clown.