In the summer of 1219 A.D., according to the plan, Genghis Khan held a grand mobilization meeting on the banks of the Yerdes River, and the armies of various nationalities from all over Mongolia gathered together, and the scene was extremely grand and spectacular.

Genghis Khan did a very thorough job of preparing for the western expedition, and he always advocated not fighting unprepared battles, especially to attack a large country like Khorezm for a long distance, and Genghis Khan did it carefully and perfectly. Genghis Khan finished the review according to the routine, and finally decided to leave Temuge Chijin to guard the Mongol camp, and ordered the youngest Empress Hulan to accompany him on the western expedition to relieve his worries and boredom in the battle.

At the conference, Genghis Khan announced that Mu Huali would continue to attack the Jin State, and send Hazar to lead his troops to deal with Western Xia, adopting the strategy of besieging but not fighting, and monitoring its movements. Then he ordered several generals who had distinguished themselves in the previous campaigns to lead the front team, with the general Jebe as the vanguard, followed by the men of Subutai, and then the team led by Tokuchaer.

Genghis Khan led his four sons and generals to lead 100,000 horses to respond, so they lined up and set off with flags. The mighty army had just gone not far, when suddenly a strong wind rose and black clouds were thick, and in an instant the snow fluttered and flew down, and in less than half an hour, the ground was covered with snow for several inches.

When Genghis Khan saw it, he couldn't help but say unhappily: "Now it's summer, the weather should be hot, why is it snowing heavily?"

At this time, a person suddenly came out from the side and said: "Great Khan, please don't question it, the sudden cold in the middle of summer is a killing weather from heaven, which shows that our Mongolian army is seeking revenge from Fengtian, isn't it a sign of great luck?"

When Genghis Khan saw that it was Yelu Chucai, he knew that he was well-read, knowledgeable, and knowledgeable, so he was convinced. He looked at Yelu Chucai happily, and said: "The people of Khorezm have acted perversely, killing innocents in vain, and they should be requisitioned, and we are doing this for the sake of heaven, and this teacher of benevolence and righteousness will naturally be blessed by the immortal heaven." ”

Genghis Khan saw the heavy snow as a sign of the snow, and he commanded his army to the west. More than 100,000 cavalry, hundreds of thousands of war horses, plus ox carts for transport, constitute a vast and magnificent team, which is overwhelming and intimidating from a distance.

The army came to the foot of the Golden Mountain, and although the snow was flying on the mountain and the ice was accumulating thousands of feet, the valley was covered with strange flowers and plants, which was really a magical place. In order to meet the needs of the march, Genghis Khan ordered to dig ice to open the road, and he let the third son Wo Kotai be in charge, leading the sappers to shovel ice and build roads in the Altai Mountains; and sent the second son Chagatai to lead the troops to build plank roads, and 48 bridges were erected alone, and the difficulties of the roads were no less than the difficulties of the Shu Road.

Despite the difficulties and dangers of the road, the Mongol army overcame many difficulties with amazing perseverance, crossed the Altai Mountains, crossed the valley between the Pamirs and the Tien Shan, and created a miracle on earth after a long journey to carve out a marching path in the snowy icebergs and snowy mountains that are rarely inhabited.

At that time, Genghis Khan's march was mostly wide and frontal, and it is said that it took three days to travel from the left flank to the right flank, which shows the width of his marching sequence. Each column must send an advance force in advance to conduct long-distance search and vigilance, and the area of activity often covers an area of 1 or 200 miles.

In such a large-scale long-distance campaign, in addition to the traditional herd of sheep to be driven along with the army, the supplies of the troops depended in principle on the supply of military supplies from the conquered territories along the way. Although the Mongolian war horse is smaller, it can bear hardships and stand hard work, and it is also a big advantage to not pick and drink.

When the army arrived at Husi City, the capital of the former Western Liao State, Genghis Khan divided his troops into three groups, the first army first carried out a frontal attack on the entire line of the Syr Darya River to attract the enemy's attention, which was divided into three corps, the Jochi Corps, including 10,000 cavalry of the Uygurs, with felt as the first target, and swept the lower reaches of the Syr Darya River, and then traced up the river to join up with other corps.

The Chagatai and Ogedai Corps, with the first goal of the Syr Darya Army, then traced the river and swept away the enemy troops in the middle reaches of the Syr Darya River. The armies of Arahhe, Suyikbald, and Taha, along the valley of the Pakhana River, down the upper reaches of the Syr Darya, attacked the city of Kokand. After meeting near the city of Khuyu, the three corps advanced southwest to take part in the general siege of Samarkand, the capital of Khorezm.

The 25,000 men and horses led by the general Jebe secretly crossed the Green Ridge, went down the upper Amu Darya River, and surrounded Samarkan from the southeast, thus forming a pincer offensive with the First Route Army. In doing so, they would be able to go around the enemy's rear and cut off Khorezm from Afghanistan and Khorasan in the south, leaving the enemy at bay. Therefore, Jebe's army had to march in secret, and the road was difficult and dangerous, and his difficulties were unimaginable.

Before leaving, Genghis Khan prepared wine in the big tent for Jebe, and said affectionately to him, a wise and brave general: "This road is difficult and dangerous, and the tasks are heavy. ”

Jebe replied very decisively: "If the Great Khan sends me to the fire, I will go, and if the Great Khan sends me to the water, I will go too!"

The Third Route Army was the main force of the Chinese army led by Genghis Khan and his young son Tuo Lei, first concealed in the south of the Fuhe River, rested his troops and raised horses, and after the frontal troops attracted the enemy, they secretly crossed the Syr Darya River, crossed the vast and difficult Red Desert, and attacked Buhuara City from the northwest to cut off the enemy's connection between the old and new capitals, during which they had to march hard in the desert for more than half a month.

In order to prevent the enemies of Yulong Jiechi from attacking from behind, Genghis Khan also did a divisive work, taking advantage of the contradiction between Mohammad's mother and son, and sent an envoy to Yulong Jiechi to say to the Queen Mother: "Our Mongolian army has no intention of attacking Yulong Jiechi, and when all parts of the country are pacified, we should dedicate the Khorasan region to the Queen Mother." ”

Although the Queen Mother ignored it, she did not send troops from Yulong Jiechi to attack Genghis Khan from behind, which shows that the discord plan has worked.

After Genghis Khan's army had crossed the Altai Mountains, he sent an envoy to Mohammad and informed: "I am sending 200,000 troops and horses to hunt with your Excellency under the city of Rathara to settle the accounts for the murder of our caravan." ”

Mohammed immediately dispersed his army in the main cities along the Syr Darya River and on the eastern border, and soon the scouts sent by Mohammed returned to report to him about the situation of the Mongol army: "Genghis Khan's army is as numerous as locusts covering the sky and ants nesting out, and his warriors are as brave as lions, and the fatigue and danger of war are no problem for them. They don't know how to rest, they don't know how to retreat, and when they go out on battle, they take all the necessities with them. ”

"They feed their hunger with dried meat and yogurt, and they eat good and evil without choice, and they eat all kinds of animal meat, pork and dog meat. They cut the veins of their horses to suck blood, and their horses did not need grain grass and oats, but used their hooves to cut the snow and nibble on the grass. No mountain or river can stop them from advancing, and any kind of mountain pass and dangerous road can be crossed, and when they encounter a big river, they can swim across the horse, and people will grab the horse's mane and horse's tail to cross the river. ”

When he received this information, Mohammed was greatly surprised, and he remembered that he had had a clash with the Mongol army in Felt not long ago, so he did not dare to take it lightly. In order to counter the Mongol army, Mohammad immediately convened a military conference to analyze Genghis Khan's strategic intentions and study countermeasures.

The defender of the city of Sara Yinalsu first said: "The momentum of the Mongolian soldiers and horses is not small, this is a superficial phenomenon, after thousands of miles of marching, and over the mountains and mountains, it must be a lack of people and horses. As long as we hold on to the city, will they be able to fight for a long time? Moreover, they are unfamiliar with the people and the land, and they cannot bring grain and grass with them, and they are not accustomed to the water and soil, or it will not be long before they will retreat without attacking, and then we will be able to defeat them in one fell swoop. ”

Mohammed's eldest son, Zalandin, said: "As long as we insist on holding the fortified walls and clearing the wilderness, stick to the fortress, and let the Mongol army take captivity outside the city, or it will not be long before Genghis Khan will retreat." ”

However, the defender of the city, Qiulihanv, said: "The Mongol army is not only good at field battles, but I heard that they also have all kinds of artillery, and no matter how strong the city walls are, they cannot withstand the bombardment, so we have to guard against it." ”

Yina Leshu immediately sarcastic: "Hearing is false, seeing is believing, don't be frightened by that hearsay, you should face the facts." ”

Qiulihanfu was immediately furious: "Who was frightened? Didn't you recruit this Mongol? You are bold, you should lead your troops to meet and fight, why do you still propose to hold the city?"

"You tell me clearly, how did I recruit the Mongols?"

"Do you want me to tell me clearly? Where is the gold and silver treasure of the Mongol caravan? Has it been swallowed by the wolf? Who killed the four hundred and fifty Mongol merchants and messengers?"

"You nonsense! You cowardly Turkmen!"

"Don't quarrel! The Mongols are about to come to the city, what are they fighting for?"

Mohammed stopped loudly, waved his hands to the two of them, and said to everyone: "In any case, the Mongol soldiers and horses have arrived at our gate, and it is imperative that we unite and fight the enemy together." ”

At this point, the king looked at the Turkmen from Jurikhan and said in a loud voice: "I thought that Jurikhamp was right, and that the Mongols should not be taken lightly, and that I knew that the Mongols were not to be messed with in that battle with their cavalry in the felt. ”

As soon as the king said this, the Turkmen generals immediately stood up with a loud voice and said, "Report to the king, we are all cowards, let us fight this battle by Yinaleshu, let's go." ”

Mohammed immediately walked over to stop them and persuaded: "Alright, alright, please calm your anger, how can we have a split within ourselves at the moment of the great enemy?"

In the army of Khorezm, mainly Turkmen and Khammens, Turkmen were discriminated against, while Khammen were brave and warlike, and they were relatives of the king, so they were trusted in the imperial court. Those Turkmen generals often said dissatisfiedly: "We are raised by our stepmothers, and we are descendants." ”

Mohammed's mother, the bald Son, was a member of the Kangli tribe, and around her formed a powerful military aristocracy composed of Kangli-born military ministers and military commanders' younger nephews. The defender of the city of Tara was the nephew of Genkedun the Bald and the cousin of Mohammad, who relied on his aunt's power to be domineering in the army and did not take the Turkmen seriously.