The first time the human being talked about this 大同世界 on this planet was when Confucius added his reflection as one of the "Ten Wings" to the 13th Dexagram of I Ching, 易经. It was about 480BC. The name of this 13th Hexagram is 天火同人. It is leading to the talking about the unity of the world, the TaiJi, the peace of the world, the unity of the human with nature and the universe. I Ching puts humans in the middle of heaven and Mother Earth and introduces a harmonized balanced mutual relationship between humans and the world. From a modern point of view, we may expand our understanding based on the recent science and civilization development, that this unity roots from the unity of human body and mind, human physical and mental health, to the unity between people, between organization, regions, countries... Deep down, humans are part of nature. The harmonized balance between the human and nature starts from harmonized thoughts in everyone's hearts and minds.
About 2000 years later, "Utopia" was put into as a new "concept" in the 16th century, which initiated new thinkings in the western world for an ideal world to discover and pursue for the human being. It is a signal that the cultural development of the East and the West will eventually be unanimous for the common development of the beautiful, harmonious and prosperous mankind.
Being the classic of the classic, the origin of the origin, of all Chinese culture, ancient science, traditional Chinese medicine, philosophy, and etc, I Ching's theories and concepts emerged everywhere in the Chinese and China world over thousands of years, through the social and civilization development. It has always been the key moral and social quality and value of this ever-lasting great cultural country. 天人合一，has been one of the major tags of Chinese characters. 天人合一 is the best reflection and the practical principle of the 大同世界.