After Kamsa sent so many asuras to Vrindavan in an attempt to kill Sri Krishna and Sri Balaram they decided to invite them to Mathura for a wrestling match with great demons Chanura and Mustika . At that time Krishna came to Mathura. He and Balaram killed Cahnura and Mustika and then they killed Kamsa. After they killed Kamsa, Kamsa had 2 wives Asti and Prapti and they were the daughters of king Jarasandha who was a great demon of the Magad provience. They went back to their father Jarasandh and they were grief stricken and their heart were broken and weeping and weeping and they began to proclaim to their father that Kamsa was such a a nobel pious righteous man, this Krishna such a rouge, he came and when our husband Kamsa was minding his own business he was not aware Krishna jumped on him and killed him by all unfair means and we will not be satisfied until the death of our husband is avenged. So Jarasandha made a vow to destroy Krishna and destroy the entire yadu dynasty. He was a very very powerful asura so he mobilsed 23 Askhoni division of soldiers all of demons from all over the world to help him to conquer Krishna. As you now in the battle on Kurushetra so many solider were killed there were only 18 Aukshoni divisions of soldiers on both sides together and Jarasandha mob 23 Aukshoni divisions and they attacked Mathura Krishna, and Krishna he killed all of his army deeply uprooted it destroyed everyone except Jarasandha. HE allowed Jarasandha to escape. Jarasandha again went and mobilized all the demons from all over the world to come up with a huge army and again attacked Mathura and Krishna destroyed all his armies he did this 17 consequtive times. Now one may ask why Krishna killed his whole army but never would killed Jarasandha. The great acharyas explain that Krishna’s mission in this world is paritriyanam sadhu nam vinasyahca duskritiam dharma sanstamp syt samebavne yuge yuge.……He comes for the purpose of protecting his devotees and annihilating the miscreants the demons. HE knew that Jarsasndha was such a poplar and a influential demon that he was getting demons form all over the world and bringing them right to Mathura so instead of Krishna having to travel all over the world to kill alle demons he knew all he had to do was to kill them and let Jarasandha bring them back all whoever was left and kill them all and in this way the demons were coming right to his door.
There was a personality of the name Garga . One time it so happened that some of the members of the Yadu Dynasty ridiculed him and laughed at him. So he did tapasaya to Lord Shiva for a long time, many long years and he begged for a benediction that he would have child that would create great fear and anxity in the Yadus. So with the benediction of Lord Shankar he begot of a woman from a yavana class a sect most unciviised section of society a son whose name was Kalayavan, who was a very very powerful demon. And because he was form a Yavana untouchable class nobody liked to go close to him, very unclivilised. He mobilised a huge army of barbarians and Jarasandh arranged that one would attack from east and one would attack fm west simultaneously. So kalayavan comes with his armies from one side of Mathura an challenging Krishna to fight, and Krishna realized that while I am fighting with his armies, Jarasandh would come form other side, then the citizens of Mathura will be in a very very difficult postion. It would be very uncomfortable for them so He spoke with Balaram about this and He made a plan. While all the citizens of Mathura were sleeping Krishna called for Visvakarma the arthetic of the demigods and He told him to build a beautiful city within the sea. The city had a bounday wall around it which was 96 miles and Visvakarma may built such a wonderful, beautiful, uncredible palace that nobody would have seen, beautiful wide high way lanes they imported many beautiful flowers like Parijata from the heavenly places, beautiful beautiful palaces all bedecked with marble and all precious jewels and gold and silver and they even brought the Sudharma the administrative parliament building of the heavenly planets of Indralok, they brought it down to be the capital of Dwarka. And after every thing was beautifully consturcted and all the 33crores demigods all made contributions or gifts to make Dwarka beautiful. While all the inhabitant citizens of Mathura were sleeping, by the yogamaya potecnty Krishna transported every one to Dwarka, so when they woke up in the morning they were living in this beautiful beautiful city in the middle of the ocean.
So Krishna was confidant that this was a very fortified fort protected by the ocean itself and He could attempt to dealing with these demons. So when kalyavana approached Krishna he just walked right by him and Krishna just walked very fast and kalyavan was threatening you coward why don’t you stand and you fight and Krishna kept walking and he walked into a cave and kalyavan was thinking what type of nonsense cowhard he is now hiding in a cave and when he entered the cave he saw a body sleeping on the ground he thought he was Krishna, what and insult, I challenged him to fight and he went to sleep and so so very hard he kicked his body and but he was not Krishna but a great king of the name Muchukunda who immediately arose and looked at kaalyavana with great anger and form his eyes he burnt Kaalyavana ashes. Then Muchukunda told Krishna that he was a not Krishna but a great king of the name Muchukunda who immediately arose and looked at kalyavana with great anger and form his eyes he burnt Kalyavana into ashes. Then Muchukunda told Krishna that he was a king who defended the demigods for many long years against the demons until Kartikeya the son of shiva was born. At that time they told me that they do not require you any more we will give you any bendiction for your Seva he said the the only benediction I want is I want to sleep. I haven’t slept for years and he was fearing they if any other problem would take place Indra and the demigods will wake him up so he said that I want a benediction that if any one who will wake me I will brun to ashes with my eyes. Krishna was so clever but Muchukunda was His devotee and Krishna wanted to wake him to send him back to Godhead but if He woke him then Muchukunda would look at him and if He did not burn to ashes then it would have made the demigod liars and if He would have burnt to ashes then ..it is not possible He is Krishna. So He had to have somebody else to wake him up, somebody who was to meant to be burnt to ashes plus Kaalayavana was a yavana and therefore it was below the dignity of Krishna to have to touch him with His own body or any of His weapons. So He arranged it so that Muchukunda could burn him with his glance and ten He gave Muchukunda any benediction and Muchukunda asked simply let me always be remembering you with love and devotion and let me always be the servant of your devotees.
Then Krishna went back to Mathura and at that time Jarasandha attacked and when Jarasandha attacked again Krishna just walked away and Jarasandha started chasing after Him and this time Balaram was with along with Him and Krishna Balaram were walking and Jarasandha was running as fast as he can with all of his armies, aukshoni divisions of soldiers but no matter how much they ran even with their chariots and elephants and with full speed Krishna and Balarama were walking they could not reach Him and Krishna walked into a big mountain and that mountain was 80 miles tall and at that time Jarasandha and his armies searched the entire mountain but they could not find Krishna but they knew that He had not escaped so they put fire all around the mountain and lit the entire mountain on fire knowing that nobody could escape, but Krishna and Balaram from the top of the mountain they leaped over the fire 80 miles down to the gorund.
Sri Krishna Balaram Ki Jai. This mountain called mount pravarshan is even today in Gujarat state called as Raivata mountain. Meanwhile Jarasandha thought that they were dead and they had nice and wonderful celebrations that Krishna Balaram were finally dead. Because Krishna ran from front of Jarasandha he gave the name Ranchor. Ranchor literaly means the one who ran form the battle like a cowhard, but when Krishna ran from battle as Ranchor He is actually a demonstration of His opulence aiswarya of renounciation. Krishna does not care of what people think of him in this regard.He is a renounciate. He allowed everyone to think that he is cowhard running way form battle because he had a very special purpose. What was His purpose? He wanted to get to Dwarka very soon because He knew that Rukmini would soon meet Him to kidnap Her and if He fought this war with Jarasandha he might be late so he walked away, jumped over the fire and entered into Dwarka.