Story of "Barbaric"

Part 1 :  How Barbaric born ?

Two demons "Narak" and "Mura" were threatening the earth and even the swarglog. Being frightened Indra went to Dwarka and meet Lord Krishna and told him about these two demons and also told that Narak has stolen Dev mata Aditi's Kundal. He requested Krishna to finish these two demons and give earth and swarglog freedom. Krishna accepted his request and with his wife Satyabhama. who was a warrior, he attacked these two asuras riding on his divine Garurdhaj rath along with many armies.
There were massive fights between Mura, Narak and Satyabhama Krishna. At the end Krishna kills Narak and snatched the kundal. He also give freedom to 16100 ladies, whom Narak had captured. He accepted these 16100 ladies as his wife but there was no physical relation among them with Krishna.

Seeing Narak's death, Mura becomes more furious and fights more brutally than previous. Here is a twist that Mura has boon, which was given by Devi Kamakhya to his daughter "Kamkantakha", that she will save him.
But the justice says that no boon remains lasts for anyone if he does adharma. For Mura, it behaves same. The boon does not saved him, and Krishna kills Mura. That's why Krishna's another name is "Murari".
Hearing her father's death, Kamkantakha went to the battle field and started fighting. After long battle, lastly Krishna takes his Sudarshan chakra to kill her. At that time Kamakhya Devi appeared and told Kamkantakha about the personality of Lord Krishna. She also told Kamkantakha that her wish(to get a brave husband)can only be true in the hands of Lord Krishna. 
Kamkantakha than realizes her mistake and bow down to Krishna. krishna give her blessings and Married her to Ghatotkach (the son of Bhima and Hidimba)
then after few years Ghatotkach and Kamkantakha gave birth to a child, who had become famous with "BARBARIC".

Part 2: How Barbaric sacrifices his life?

Barbaric had expressed his desire to watch the war of Mahabharata to his mother. His mother agreed to let him go watch it, but asked him before leaving as to which side he would join if he felt the urge to take part in the war. Barbaric promised his mother that he would join the side that was weaker. Saying this he set up on the journey to visit the battlefield.

Krishna, having heard of Barbaric and wanting to examine Barbaric's strength, disguised himself as a brahmin and came in front of Barbaric. Krishna asked him about how many days would it take to finish the war if he were to fight it alone. Barbaric replied it would take him only 1 minute to finish the battle if he was to fight it alone. Krishna was surprised at this answer of Barbaric considering the fact that Barbaric was walking towards the battlefield with just 3 arrows and a bow. To this Barbaric explained the power of the 3 arrows.

The first arrow was supposed to mark all the objects that Barbaric wanted to be destroyed.
The second arrow was supposed to mark all the objects that Barbaric wanted to be saved.
The third arrow was supposed to destroy all the objects marked by the first arrow.

And at the end of this all the arrows would come return to the quiver. Krishna eager to test this out asked Barbaric to tie all the leaves of the tree that he was standing under. As Barbaric started meditating to perform the task, Krishna took one leaf from the tree and placed it under his foot without Barbaric's knowledge. When Barbaric releases the first arrow, the arrow marks all the leaves from the tree and eventually starts revolving around Lord Krishna's feet. Krishna asks Barbaric as to why the arrow is doing this. To this Barbaric replies that there must be a leaf under your feet and asks Krishna to lift his leg. As soon as Krishna lifts his leg, the arrow goes ahead and marks the remaining leaf too. 

This incident scares Lord Krishna about the phenomenal power of Barbaric. He concludes that the arrows are truly infallible. Krishna also realizes that in the real battlefield in case Krishna wants to isolate someone (for eg the 5 Pandavas) from Barbaric's attack, then he would not be able to do so, since even without the knowledge of Barbaric, the arrow would go ahead and destroy the target if Barbaric intended so.

To this Krishna asks Barbaric about which side he was planning to fight for in the war of Mahabharata. Barbaric explains that since the Kaurava Army is bigger than the Pandava Army and because of the condition he had agreed to with his mother, he would fight for the Pandavas. But to this Lord Krishna explains the paradox of the condition he had agreed with his mother. Krishna explains that since he was the greatest warrior on the battlefield, which ever side he joins would make the other side weaker. So eventually he would end up oscillating between the two sides and destroy everyone except himself. Thus Krishna reveals the actual consequence of the word that he had given to his mother. Thus Krishna(still disguised as a Brahmin) asks for Barbaric's head in charity to avoid his involvement in the war.

After this Krishna explains that it was necessary to sacrifice the head of the greatest Kshatriya in order to worship the battlefield and that he regarded Barbaric as the greatest Kshatriya of that time.

Before actually giving his head, Barbaric expresses his desire to view the forthcoming battle. To this Krishna agreed to place Barbaric's head on top of the mountain that overlooked the battlefield. 

At the end of the war, the Pandavas argued among themselves about whose was the greatest contribution to their victory. To this Krishna suggests that Barbaric's head should be allowed to judge this since it has watched the entire war. Barbaric's head suggests it was Krishna alone who was responsible for the victory in the war. His advice, his strategy and his presence was crucial in the victory.

Barbaric has given another name by Krishna : "KHATU SHYAM"