The ancient people who lived in the Northeast Asia, such as Mongolia, Siberia, Manchuria were equestrians, nomads and hunters. Their life required continuous move from one place to another for better grass fields and game and they needed to adjust themselves to the frequent changes of environments.

Their lifestyle and continuous relocation were mainly motivated by the changes of the Sun, the moon and the stars. They slowly and naturally began to recognize through accumulated experiences and observations that there was certain rule in the changes of nature, the universe and the lives around them.

They thought the fundamental source behind all of these changes was Ki. It was the inception of the concept of Ki. For them, time, space, energy, materials, nature and human beings were only a different aspects or transformations of the same one Ki. This understanding of nature is precisely the same as modern physics. In modern physics, it is also said that time and space, material and mind, and energy and movements can be merged into one. From this Ki perspective, everything else forming the universe was explainable using the concept of Ki. From this understanding, they developed a practice to attain the power of Ki, Sun Do, the way of receiving universal life energy which was mostly represented by the power and virtue of the Sun.

This understanding of the flow of Ki was later adopted by the people who developed the I Ching, from which the core notions are Yin (- energy), Yang (+ energy) and the Five Elements of Water, Wood, Fire, Metal and Earth are derived.

For the nomads, the main observable objects in the sky representing the Ki were the Sun, the Yang energy and the Moon, the Yin energy.

Sun Do practices this Ki and attains the power and virtue of Ki and in order to live in harmony with all beings. The leaders of ancient Northeast Asia were persons who accomplished this goal by practicing Ki.