The 10-century process of Indianization of Indonesia was rivaled by the coming of Persian Sufism, and Sufism had begun to take root in the native philosophical discourse since the early 15th century onwards. The widespread practice of Sufism was encouraged by the massive founding of Islamic kingdoms and sultanates in Indonesia (Nasr 1991:262). Kings and sultans like Sunan Giri, Sunan Gunungjati, Sunan Kudus, Sultan Trenggono of Demak, Pakubuwana II, Pakubuwana IV, Sultan Ageng Tirtayasa of Banten, Sultan Alauddin Riayat Syah, Engku Hajji Muda Raja Abdallah to Raja Muhammad Yusuf are "sufi-kings"; they learned Sufism from eminent Sufi teachers (Perpustakaan Nasional 2001:12-39).