how did peoples interchange their idea
Answers
Answer:
Today we have internet forums. Back in Roman times they had real forums. These were big spaces in the middle of cities in which people gathered together and exchanged ideas with each other. Like many things in their culture, the Romans stole Forums from the Ancient Greeks.
Answer:
Throughout human history we learned from the other people. The key to idea exchange lies in observation. While the Internet has improved the speed of communication it did nothing to improve the key aspect of learning - observation. This key human skill has been with us throughout. Let's say I notice that you have a better way to hunt deer - a task takes me days to finish, I will imitate your method. If I didn't imitate, I would perish [as you would hunt all the deer]. Thus, learning was often a survival requirement. In some sense, the people you see now are descendents of those who were open to imitation. Humans learned whenever they interacted with people other cultures.
However, the problem is that the interaction was often limited by geography. Once people settled in a region with abundant food resources, they were mostly disconnected from the rest of humanity. Thus, you see plenty of cultures that never changed much in thousands of years.
Before the contemporary era, there were two main groups of people who helped spread ideas. These were the merchants and the religious missionaries. Both of these had a significant urging to travel long distances and learn distant cultures. For gold and heaven, they would risk everything they have and their risk taking was how ideas moved around.
For the most part in human history, the agendas of merchants and missionaries were highly intermingled. Merchants helped spread religions, starting from the first missionary religion of Buddhism and eventually, Christianity and Islam. For the merchants the key motivation was to find the exotic things that might impress their Emperor, Maharajah or Sultan. Like bees in search of honey, they were busy, curious and helped cross-pollinate. Religions often returned the favor by making it easy for the merchants to interact and often even housed the traveling merchants in their churches, temples and mosques.