Parikshit and Kali

After the great war between the forces of good and evil (Mahabharata), Lord Krishna returns to Dwaraka. The Yadava dynasty including Balarama and Sri Krishna, comes to an end after 36 years from the end of the Kurukshetra war. (Exactly as per a curse given by Gandhari, who herself was an ardent devotee of Lord Krishna.)

The news of return of Sri Krishna to Vaikuntha was too much for the Pandavas to take and they were unable to subdue their grief. They decide to leave the kingdom for sanyasa by crowning their only descendant, Parikshit as the king of Hastinapur. King Parikshit, son of Abhimanyu and Uttara and was born after the great war. (All other descendants of Pandavas were murdered in the war, while Parikshit was saved by the divine grace of Sri Krishna.) Parikshit was an able ruler who was just and compassionate and looked after the welfare of his people.

One day, king Parikshit sees a bull and cow being beaten by a shudra. The bull had been injured on 3 legs and was supporting its weight on the remaining leg. The shudra was beating the bull on its remaining 1 leg. The king recognizes the shudra to be Kali. King Parikshit raises his sword to kill Kali for his unjust act. Kali begs for his forgiveness and tells him that the yugas - Satya yuga, Treta yuga, Dwapara yuga and finaly, Kali yuga had to go in cycles and that, that was the law of nature. Dwapara yuga had ended at the time of Kurukshetra war and Kali yuga had begone on the demise of Lord Krishna. Kali could not enter the world as long as Sri Krishna prevailed over mother Earth. But in His absence, Kali started spreading his wings over the world. Yet he could not enter Parikshit's kingdom, because he was a just and righteous ruler. Reminding him that the Yugas had to go in the cycle, he asks Parikshit to let him enter his kingdom. King Parikshit decides to let Kali into his country, but only partially. King Parikshit said that he could enter his kingdom in only these 5 places:

In houses of gambling, in taverns, in brothels, in places where animals are killed and in gold. Kali agrees to this and marches to his new abodes. King Parikshit does not realize, that he too was wearing a crown made of Gold.

Conclusion:

Later, Kali enters the crown of king Parikshit and makes him do an unrighteous act, that results in his death.

The distraught cow in this story is the representation of mother earth and the Bull with 3 weakened legs is the representation of Dharma (religious / moral principles). Every society (Cow) is in balance when the world and all its living organisms follow the codes of Dharma (Bull). It is said that the 4 yugas, occur in cycles, and in each yuga, one quarter of Dharma is lost. hence in Satya Yuga, Dharma is instilled completely in the world, In Treta yuga, and Dwapara yuga, one quarter each of Dharma vanishes. Thus, in Kali yuga, only one quarter of Dharma remains, signified by the 1 remaining leg of the bull. (It also signifies that 3 quarters of the world have turned irreligious.) Mother earth as signified by the cow was saddened by acts of men who kill and eat cows and bulls - in terms of the animals themselves as well as their symbolism.

In general, Kali "kaala" is signified with the increase in diseases, separation from near and dear ones, lack of sacrifices offered by men, failure of marriages, neglect of women and children, separation of education and moral principals and lack of observance of social and moral rules among st other things.