Demon King Shumbha was mesmerized by reports of Goddess Durga's beauty. He wished to marry her and sent two demon commanders, Chanda and Munda, to bring her to him. When Chanda and Munda confronted Durga, her face darkened with anger. The black Goddess Kali (Kali means "black"), wearing a garland of human heads and a saree made of tiger skin, sprang from Durga's forehead.
Goddess Kali fought Chanda and Munda and finally beheaded the two demons. She presented their severed heads to Goddess Durga, who was pleased.
"These are not merely the heads of two demons," said Durga to Kali. "They are the heads of sin and atrocity. By killing these destructive demons, you have saved humankind from their tyranny. You will henceforth be known as Chamunda, meaning 'slayer of Chanda and Munda.'"
"Thank you. I will add their heads to my garland," replied Kali.
Shumbh then sent Mahishasura's brother, Raktabija (the reincarnation of Rambha), to fight Kali. Raktabija had received a boon from Lord Shiva that a new version of himself would be born from each drop of his blood that fell on the battlefield. (That was how Raktabija got his name, which means "blood seed.") Raktabija and Kali fought a fierce battle, but each time Raktabija was wounded and his blood fell on the battlefield, new versions of himself sprang from the ground.
Durga then told Kali to drink the blood flowing from Raktabija's body before it hit the ground. So Durga attacked the various versions of Raktabija while Kali drank their blood. In this way, the two Goddesses killed all the versions of Raktabaja.
Even after Raktabija's death, Kali's thirst for blood was not satisfied, and she went on a killing spree. To stop her, Lord Shiva lay in her path. When Kali realized she had accidentally stepped on her husband, she stuck her tongue out in embarrassment. Her fury was calmed, and she begged Shiva for forgiveness.