other decisions of Genghis, it can be said that Genghis was familiar with the geographical situation of Transoxania really well. The conquest of Bukhara, Samarkand and Otrar In 1220, Genghis Khan attacked Bukhara with the main forces of his army. The Sultan was caught completely unaware. He had anticipated that Genghis would attack Samarkand first, where both his field army and the garrison stationed at Bukhara would relieve the siege. The Khan's march through the Kyzylkum had left his field army impotent, unable to either engage the enemy or help his people. The Khan faced strong resistance from the defenders of the city; But this resistance did not last long. The city fell in less than two weeks, because the city's communication routes was cut off from all sides, they gave up their resistance Inevitably. After capturing Bukhara, the Mongol invaders killed thousands of unarmed and defenseless citizens and took the rest as slaves. Genghis summoned the elders of Bukhara and told them that the purpose of summoning them is collecting the assets that Sultan Muhammad sold to merchants (The Otrar incident), because these objects belong to Mongols. They brought all the property they had from Otrar caravan and handed them over to the Genghis Khan. Then they took the road to Samarkand. Sultan Mohammad had emphasized greatly to defense of Samarkand and had gathered a large force in this city and the fortifications of the city had been repaired. According to various historians, between 50,000 to 110,000 soldiers had gathered in Samarkand to defend the city. It seems that the city could have resisted the siege for several years. On the third day of the siege, a group from defenders of the city came out of their positions and attacked the enemy. They killed some of the Mongol soldiers, but then they were surrounded by the enemy, and most of them perished on the battlefield. This unsuccessful attack had an unfortunate effect on the morale of the defenders. Some influential people of the city decided to surrender and sent the judge and Shaykh al-Islām of the city to Genghis Khan to talk about surrender. Finally, they opened the gate of the city to the enemy, and Genghis' army entered the city and massacred and looted the people. After the attack, the city of Samarkand became a ruin and was deserted. Mongol soldiers took the city of Otrar after a