Who Killed Sultan Tengah?

The story of Sultan Tengah ends abruptly. Throughout his life, Sultan Tengah was a tireless Caller to Islam and was a guest in the royal courts of three kingdoms. Returning from an odyssey of 40 years, he was assassinated by one of his own followers within the shadow of the solitary mountain that marked his domain. What clues to his murder can we find in the legend of Sultan Tengah?