The Eurasian civilizations grew out of the nomadic and indigenous tribes over thousands of years; pre-biblical tribes lived either in farmlands or traveled between villages. Over time, tribes joined together to defend their lands or expand their territories, and the three major civilizations formed: the Middle Eastern tribes, with focus on Islam, the Chinese tribes, with focus on Buddhism, and the European tribes, with focus on Christianity. Each local civilization developed their own unique writings, histories, and trading commodities.
Although in pre-Biblical times many civilizations took pains to keep themselves separated, trade routes brought many of them together in various ways. The first and most common of those was the famous Silk Road, which comprised trade routes throughout Eurasia and eventually became the most used trade route until the common advent of Ocean Travel. Groups and single traders would stop between villages and kingdoms to trade unique goods and stories; many of the stories told in these visits became common knowledge and/or tradition in multiple nations, even if the story specifically originated in another part of the world.
Europe was also blocked from easy access by its numerous mountain ranges, so trade was infrequent until ships began sailing between the coasts, making travel easier; because of this, the Middle East and Asia were often thought of as far-away, mysterious places, only visited by famous and wealthy travelers like Marco Polo. However, as China's Dynastic cultures continued to flourish, the Kangxi Emperor started the trend of adopting science and philosophy from other nations, even as he increased research and technology emerging from China itself. Meanwhile, the Middle Eastern nations were establishing a base of powerful, insular tribes with strong knowledge of mathematics, giving them leverage in architecture, science, and economic factors. Trade between the Middle East and China was often disrupted by invading Nomad tribes, as well as influence from developing Russia to the north.
By the time the European nations began to spread their influence, "discovering" the Americas and establishing colonies, contact between the Eurasian civilizations was mostly relegated to trade of commodities; there was little or no spread of religion or culture beyond the lands that each civilization deliberately annexed. Ocean travel and the sudden influx of goods from the Americas caused new interest in trade, and the desire of each culture to be insulated from the outside began to wane.