According to Genghis Khan: A Biography by Zofia Stone, "It was not originally the intention of the Mongol Empire to invade the Khwarezmid Empire. According to the Persian historian Juzjani, Genghis Khan had originally sent the ruler of the Khwarezmid Empire, Ala ad-Din Muhammad, a message seeking trade and greeted him as his neighbor: 'I am master of the lands of the rising sun while you rule those of the setting sun. Let us conclude a firm treaty of friendship and peace.' or he said 'I am Khan of the lands of the rising sun while you are sultan of those of the setting sun: Let us conclude a firm agreement of friendship and peace'"