Story of origin of Matangi Mahavidya associated with Matanga Rishi is found in Brahma Yamala. It is believed that Matanga Rishi performed intense penance for several years and finally Goddess Shakti appeared in the form of Goddess Matangi Mahavidya before him.
Another belief is that Matanga Rishi performed intense penance to get rid of evil forces from earth. Evil had raised its head so much that it was impossible for good to survive.
To answer the prayers of Matanga Rishi, a powerful light appeared from the eyes of Goddess Tripura Sundari. That powerful light then appeared as Goddess Kali and then she took the form of Raja Matangi Mahavidya.
Matangi Mahavidya is also known as Maha Pishachini and Ucchista Chandalini. Other names of this form of Goddess Shakti are Ucchista Matangi, Raja Matangi, Sumukhi, Vaishya Matangi, Karna Matangi etc.