had to deal with the Hoi-yin Irgen rebellion in Siberia in 1216. So he didn't want to start another war. Economic factors Due to their primitiveness, the Tatar people had an urgent need for the goods of more advanced regions; therefore, it was very important for them to keep trade routes open since ancient times. From the beginning of his Monarchy, Genghis Khan attached great importance to commerce because he needed to procure weapons from India and Damascus; he also needed markets to sell Mongolian and Chinese products. But the conflict between Sultan Muhammad and Kuchlug Khan, the leader of the Naimans, had caused the closure of the roads and the interruption between the east and west trade. At the same time as this interruption in the land routes, the sea route of the Persian Gulf was also blocked due to the war between the ruler of Kish and the ruler of Hormuz, which resulted in a trade crisis in the Central Asian region. The merchants wanted the end of the conflicts and the opening of the roads. Hence, In the Mongols' attacks, some Muslim merchants helped Genghis to progress to the west. To solve this crisis, Kuchlug Khan was killed by the Mongols in 1218. Sultan Muhammad didn't care to the importance of trade relations with the Far East and the location of his land on the Silk Road, and he was indifferent to the merchants' needs and the Genghis' wishes, so after removing Kuchlug Khan, it was Sultan Muhammad's turn. The support of the Abbasid caliph from the Mongols Although the possibility that Al-Nasir encouraged the Mongols to attack the Persia is not seem unlikely due to his enmity with Khwarazmian, the customs and rituals of this caliph's statecraft; but probably, Genghis didn't paid attention to Al-Nasir's inclinations in those days. Nevertheless, some historians have pointed to the role of the Caliph in the Mongol attack on Khwarazmia, and have stated that sending an ambassador from Abbasid Caliphate to Mongol Empire and Publicizing the enmity of the Abbasid Caliph with Sultan Muhammad and giving some pieces information about the condition of the Islamic states, has not been unaffected on Genghis' desire to attack Khwarazmia. Zia al-Din ibn Athir, Iraqi translator and poet of that era, writes as follows in mentioning the reasons for Mongols attack on Islamic lands: Allahyar Khalatbari, a Persian Historian, believes that Ibn Athir did