In Asia, the spread of Islam created a new empire and Islamic Golden Age with trade among the Asian, African and European continents, and advances in science in the medieval Islamic world. East Asia experienced the full establishment of power of Imperial China, which established several prosperous dynasties influencing Korea, Vietnam, and Japan. Religions such as Buddhism and Neo-Confucianism spread in the region. Gunpowder was developed in China during the post-classical era. The Mongol Empire connected Europe and Asia, creating safe trade and stability between the two regions. In total the population of the world doubled in the time period from approximately 210 million in 500 AD to 461 million in 1500 AD. Population generally grew steadily throughout the period but endured some incidental declines in events including the Plague of Justinian, The Mongol Invasions, Muslim conquests of the Indian subcontinent, and the Black Death.