Explore developments that made Southeast Asia a dynamic and important area of the World in the period before 1450 CE, Topic 1.3 in AP World History: Modern. Productive agricultural and interregional trade contributed to Southeast Asian cultures in mainland and island Southeast Asia. Interregional exchange brought Buddhism, Hinduism, and Islam to these areas, where they syncretized with each other and local traditions. Powerful states, including the Khmer and Majapahit Empires, based their authority on these traditions. Knowledge of Southeast Asia spread across Eurasia along with its valuable trade goods, making the region a part of the "Global Middle Ages."