An interesting thing would be who would handle medieval trade between the Mediterranean basin and India and China? Would Christian Arab traders control the trade routes? Would we see a Christian Bengal and Indonesia? Could we see a Buddhist or Manichean Central Asia and Iran? Possibly Arab Buddhist or Manichean Oman?
It would be pretty fun to make a no-Islam TL where the Sassanids collapse and Manichean universalists take over, spreading their religion to the Yemen and Oman. A mostly unified Christianity still reigns in the Mediterranean basin, but Manicheaism spreads to India, Indonesia, and eventually China. Christian Crusades eliminate a Manichean Iran and Mesopotamia, but the Manichees survive in Asia and Manicheaism becomes the fourth traditional religion of China. That sounds like an interesting and fun TL.
It would be pretty fun to make a no-Islam TL where the Sassanids collapse and Manichean universalists take over, spreading their religion to the Yemen and Oman. A mostly unified Christianity still reigns in the Mediterranean basin, but Manicheaism spreads to India, Indonesia, and eventually China. Christian Crusades eliminate a Manichean Iran and Mesopotamia, but the Manichees survive in Asia and Manicheaism becomes the fourth traditional religion of China. That sounds like an interesting and fun TL.