The wind horse is a symbol of the human soul in the shamanistic tradition of East Asia and Central Asia. In Tibetan Buddhism, it was included as the pivotal element in the center of the four animals [Tiger, Garuda, Snowlion and Dragon] symbolizing the cardinal directions and a symbol of the idea of well-being or good fortune.
It has also given the name to a type of prayer flag that has the five animals printed on it.
The origins of the wind horse lie in the territory of present-day Mongolia as a component of Tengrism, as well as in Tibet in the Bon faith.
Source: Wikipedia