This book considers documented connections and raises comparisons among Eurasian societies around the year 1000; using a global frame, it aims to sketch their distinctive characteristics. Scholars of Japan, China, the steppe regions, India, and the Islamic world, Byzantium, and Western Europe concur that a remarkable diversification of different cultures accompanied demographic and economic growth worldwide. Their sketches of various Eurasian "worlds" suggest a meaningful approach to both world and global History. Some factors, like climate change, fostered interaction; others, like the invasions of nomadic peoples, checked interaction less than previously believed. The authors also demonstrate how trade, exchange transactions, and universalist religions contributed to greater interaction.