In the 11th century, a turbulent period occurred in the history of Maritime Southeast Asia. The Indian Chola navy crossed the ocean and attacked the Srivijaya kingdom of Sangrama Vijayatungavarman in Kadaram (Kedah), the capital of the powerful maritime kingdom was sacked and the king was taken captive. Along with Kadaram, Pannai in present-day Sumatra and Malaiyur and the Malayan peninsula were attacked too. Soon after that, the king of Kedah Phra Ong Mahawangsa became the first ruler to abandon the traditional Hindu faith, and converted to Islam with the Sultanate of Kedah established in year 1136. Samudera Pasai converted to Islam in the year 1267, the King of Malacca Parameswara married the princess of Pasai, and the son became the first sultan of Malacca. Soon, Malacca became the center of Islamic study and maritime trade, and other rulers followed suit. Indonesian religious leader and Islamic scholar Hamka (1908–1981) wrote in 1961: "The development of Islam in Indonesia and Malaya is intimately related to a Chinese Muslim, Admiral Zheng He."