Everybody knows him as Genghis khan(成吉思汗), but actually Genghis khan is just a respectful title as the king of the Mongol tribes at that time. Before he becomes a real king of their tribes, his name is Temujin（铁木真） in fact. In his childhood time, the Mongol groups were under the control of Jin emperor（金朝）. Jin treated Mongol crucial and merciless; Temujin grew up with a wish to revenge his relatives and ancestors killed by the Jin. Despite his difficult childhood, Temujin grew up strong enough to claim his hereditary position as tribal leader.
In 1206，Temujin was selected as the Genghis khan for Mongol tribes, the title means the great ocean. After Genghis khan had united Mongol tribes, before long he started the rebellious war against the crucial Jin emperor.
(Genghis Khan 's Army)
In the august of 1211，Genghis Khan attacked Jin at the Yehuling Great Wall（野狐岭长城）. The general of Jin side is Wanyan Chengyu（完颜承裕）, he decided to scatter his main troops to guard and fort along the Yehuling Great Wall with the strategy of as long as Genghis khan can not pass the great wall fortification, he is no treat. But Genghis khan saw through Wanyan’S plan, Genghis khan noticed that the main force of the enemy army has been scattered to guard the great wall, hence leave center of the troop with not enough defending force. Hence, Genghis khan decided to spent all the effort together at the weakest center point of the wanyan’s army and before long, the battle was indicating the victory of Genghis khan. Because, soon after Genghis khan attacked the Yehuling great wall, Wanyan had realized that he had made a huge mistake as it was too late to call enough troops back from the great wall to fight and defend.
(Map of Yehuling battle between Genghis Khan with Jin)
The Yehuling great wall victory was a big success of Genghis khan ‘s army and expellant battle in aspect of military speaking. It had also laid a firm stone for Genghis khan’s conquer of the Jin emperor and victory over the Juyongguan pass battle in the future.
Through this battle, Genghis khan had defeated 100,000 enemy forces which was the best defend troops of the Jin out of their 450,000 soldiers army.
Soon after Genghis khan had took over the Guhuling great wall area of Jin, in 1213, he swept down his army along the way to Jin ‘s capital city ——Zhongdu中都(Beijing, Today) . In order to over capital city, they have to conquer the Juyongguan pass first. The Juyongguan pass（居庸关） on the great wall, like all the others fortifications were built to protect the central emperor and defend themselves against the foreign invasion, been made stones and bricks, Juyongguan pass enjoys the title of the greatest pass under heaven.
(Juyongguan Pass rebulit by Ming dynasty)
Genghis khan’s general Zhebie（哲别） was wise enough to see that Juyongguan was not easy to conquer and better do this battle in a tricky way. Therefore, instead of the Jin army face-to-face, Zhebie had made his army pretend to fail and run when they were fighting. The general of Jin side Wanyan Fuxing fell for Zhebie’S trick, he ordered Jin army to get out the Juyongguan Great Wall and run after the Mongol army to defeat them. Yet only after Wanyan had sent his forces out the Juyongguan Great Wall, he realized that this was a trick. Wanyan’s army encountered a merciless fought back by Genghis khan. Meanwhile, another troop of Genghis khans’ army had carved down south to take over the Zijingguan Pass（紫荆关） of Great Wall, and fought back up to took over the Juyongguan pass on the other side. In the end, Juyongguan pass was conquered by Genghis khan with the strategy of lure the main force of Jin army out of great wall and then fight both side of the wall. Again, this is another typical example for Genghis Khan being a great king in the respect of military talent.
After Genghis khan had taken over the Juyongguan pass, his swept his army to Zhongdu(中都), the capital city of Jin emperor. In 1214, Jin offered gold, silk and princess to make peace with Genghis khan, then Genghis khan left the Zhongdu with loads of treasures and took away his army occupying the Juyongguan pass. Later in August of 1214, the new king of Jin had decided to change his capital city to Nanjing(Kaifeng city in Henan province in today) scared in the shadow of Genghis khan would swept down and invade Zhongdu(中都) again.
When Genghis khan ‘s army was conquering to the west area, he tried to make an ally with Xixia(西夏) emperor in the west China. But Xixia had refused Genghis khan’s proposal and made an ally with Jin emperor instead. Hence, Genghis Khan had determined to take over Xixia emperor as well. But when he was in the battle of conquering the capital city of Xixia, Genghis khan was in heavily sick. Before Genghis khan dead, he made an order with his sons and generals:1. Don’t announce my death in case the enemy had no fear and fight back instead; 2.when we conquer the Jin emperor, we should make an ally with the Song emperor, because this two emperors had always been an enemy with each other.
After Genghis khan dead, his son Wokuotai(窝阔台) took over his flag and followed his will, under his guide of taking over Jin by making ally with Song, in 1233, Jin’s capital was conquered. In 1234, Jin Emperor collapsed and replaced by Yuan Emperor of the Great Genghis Khan.