History is the activity of people in a geographical environment. The following are some personal opinions:
Since Greece is a mountainous area, it does not have more convenient land transportation like Rome in Italy. Therefore, many areas can only form relatively decentralized city-state systems. Subsequently, due to less cultivated land in mountainous areas, the population problem has produced two results. One is to carry out overseas colonization like Athens to solve the problem of overpopulation (Greek democracy also mainly Refers to Athens), and the second is to scrimp and militarize the country like Sparta. Greece's overseas colonies brought a large amount of wealth to the mother state, allowing it to develop the humanities and natural sciences. This, as well as the national characteristics of the previously invaded Achaeans, produced the foundation of Greece's democracy
On the other hand, due to the continuity of the sea, Greece's development of navigation and the subsequent war with Persia made the navy composed of civilians play a greater role than the army composed of nobles. In addition, the rulers at the time (mainly Pericles of Athens) expanded democracy from a smaller scope to a larger class scope.
However, the democracy within Athens did not expand further outwards. The Athenian Alliance that was later formed actually used its strength to impose itself on the Greek states, which eventually led to the conflict between the states headed by Sparta and Athens. The alliance's struggle for hegemony - the Peloponnesian War, Athens' failure in the war led to the decline of Greek democracy
I don't know much about Chinese democracy. I only know that there was the initial Zhou Dynasty in Chinese history. From the feudal system of the Qin and Han dynasties to the prefecture and county system of the Qin and Han dynasties, royal power shifted from decentralization to centralization, and there was no democracy like Athens. This may be due to the geographical unification of China and the influence of the original family patriarch system. There is a saying that because the Yellow River basin is vast, a large number of manpower are needed to centralize the management of the Yellow River, so the concentration of power is needed (somewhat similar to Dayu's view of water control)
China's modern democracy is almost entirely the result of external imposed influence