Final answer:
The spread of Islam to Southeast Asia around the thirteenth century, intertwined with the growth of trade and the influence of kingdoms like the Khmer Empire, represents possibly the most significant turning point in Southeast Asian history between 600-1500CE.
Step-by-step explanation:
The Largest Turning Point in Southeast Asian History (600-1500CE)
One could consider the spread of Islam to Southeast Asia in the thirteenth century as the largest turning point in Southeast Asian history between 600-1500CE. The arrival of Islam, primarily through merchant activities and Sufi missionaries, coincided with evolving trade routes and a burgeoning commercial revolution. This religious and economic transformation led to Islam's dominance in many parts of the region, particularly in the Malay Peninsula, Sumatra, and northern Java by the fifteenth century. Concurrently, kingdoms like the Khmer Empire and Srivijaya became regional powers, heavily influenced by the religious and trade dynamics of the era.
During this period, trade significantly affected the political and social structures, leading to the quantum leap in trade growth from the ninth century onwards. The resultant commercial revolution changed many aspects of life and governance across East Asia, affecting mainland, peninsula, and archipelago societies alike. The impact of trade on Southeast Asia's development cannot be overstated with the Silk Roads and Indian Ocean Trade Routes playing pivotal roles.
The thirteenth-century expansion of the Khmer Empire demonstrated the interaction between commerce, religious influence, and state power, marking another major turning point. The prominence of Hinduism and Buddhism in the empire juxtaposed with the Islamic wave that later washed over the region, underlining the dynamic and transformative nature of Southeast Asian history in this era.