I want to test the ability of students to read a passage and answer questions about it. Could you please come up with a good question for the passage "There were tax exemptions for religious figures and, to some extent, teachers and doctors. The Mongol Empire practiced religious tolerance because Mongol tradition had long held that religion was a personal concept, and not subject to law or interference.[citation needed] Sometime before the rise of Genghis Khan, Ong Khan, his mentor and eventual rival, had converted to Nestorian Christianity. Various Mongol tribes were Shamanist, Buddhist or Christian. Religious tolerance was thus a well established concept on the Asian steppe."? 

What was the final relationship between Genghis Khan and Ong Khan?