In Afro-Eurasia, all agrarian civilizations were linked together into a vast interconnected network by the beginning of the Common Era. This network involved not only the trading of material goods, but also the trading of social, religious, and philosophical ideas, languages, new technologies, and disease. The most important exchange system that existed anywhere during the Common Era is known today as the Silk Roads, but significant smaller connections developed much earlier between many of the agrarian civilizations.
