Srivijaya kingdom on Sumatra island had developed into the dominant power of Maritime Southeast Asia by the 5th century. Its capital Palembang became a major seaport and functioned as an entrepot on the Spice Route between India and China. Srivijaya was also a notable centre of Vajrayana Buddhist learning and influence. Around the 6th century CE, Malay merchants began sailing to Srivijaya where goods were transhipped directly on Sumatran ports. The winds of the Northeast Monsoon during October to December prevented sailing ships to proceed directly from the Indian Ocean to the South China Sea. The third system involved direct trade between the Indian and Chinese coasts during the Southwest Monsoon season. Srivijaya's wealth and influence faded when changes in nautical technology in the 10th century enabled Chinese and Indian merchants to ship cargo directly between their countries and also enabled the Chola state in southern India to carry out a series of destructive attacks on Srivijaya's possessions, ending Palembang's entrepot function.