Usually we just talk about four ancient civilizations: ancient Egypt, Babylon, India and China, but this is not a scientific expression. In recent decades, international historians tend to have a more general view of the "four civilized regions", that is, the civilized regions in the eastern Mediterranean (Egypt, Mesopotamia, Assyria, Phoenicia, Greece, etc. ), South Asian subcontinent civilization area (India and its surrounding areas), East Asian civilization area (China and its surrounding areas), Central and South American Indian civilization area (Maya, Aztec, Inca).

In addition, the British historian Tom Imby's classification is also different and influential.

The scientific and technological achievements created by the four ancient civilizations have made great contributions to the development history of human civilization. They have many similarities and differences. They all originated in the great river basin, where the natural geographical conditions are superior, especially the rivers provide fertile alluvial plains and favorable irrigation conditions, which greatly promote the development of agriculture, thus developing other science and technology and creating great ancient civilization. At the same time, their science and technology all come from social practice, belonging to the same type, that is, the agricultural practice mode of the Bronze Age. This makes their science and technology have similarities in many aspects and has made brilliant achievements in many aspects. However, due to the differences in production practice, there are still many differences in their science and technology. Egypt pays more attention to geometry because of the need to re-measure the land after the Nile floods. At the same time, people developed their medicine to preserve corpses, and the pyramids also reflected their great achievements in engineering. Babylon, on the other hand, relies on astronomical calendar for agricultural production, so its astronomical calendar is relatively developed and its arithmetic achievements are also very outstanding; India, on the other hand, is greatly influenced by religion, medicine is relatively developed, and people attach importance to pure thinking. Buddhism is the religion with the highest philosophical level in the world. On the basis of practice, our ancestors created developed handicrafts and accumulated rich theoretical achievements, but they were not or rarely dominated and infiltrated by religious thoughts.