The story of origin of Goddess Chamunda is an interesting one. Once two powerful demons Shumbh and Nishumba were tormenting the three worlds. The celestials went to the Himalayas and started worshipping Goddess Durga. The benevolent goddess came to the Himalayas on the call of celestials in the form of Goddess Parvati. She assured the celestials that she will kill Shumbha and Nisumbha with their attendants. Then the Goddess assumed a beautiful form and started living in the Himalayas, once Chanda and Munda two generals of demon Shumbha came to that place and saw the beautiful Goddess. They went and informed Shumbha and advised him to marry the beautiful Goddess.
Goddess Chamunda is a fierce form of Goddess Durga. She is also known as Goddess Kalika. She is adored by devotees for her fearsome prowess. Devotees worship Goddess Chamunda to get protection from enemies, diseases and sudden mishaps in life. She blesses her worshippers with happiness and prosperity.
Shumbha sent his army general Dhumralochan to capture the Goddess Durga. However she burnt him into ashes with a single roar. Shumbha became very angry at the death of his army general. He sent his generals Chanda and Munda to capture Goddess Durga. Chanda and Munda reached the mountain peak where the well armed Goddess was sitting on her lion. The two army generals encircled the Goddess with their army.
The Goddess became angry and assumed the form of fierce Kalika. This Goddess killed the entire army of Chanda and Munda and cut of their heads with her big sword. As she killed Chanda and Munda, for this reason she came to be known as Goddess Chamunda.