The fourth section of the Skanda Purana - the Kashi Khanda (which has been approximately dated to the 14th century CE) mentions various groupings of goddesses, amongst which are the Nine Durgas - protecting goddesses related to the Eight Directions and the centre. During the October Navaratri festival, each of the Nine Durgas are worshipped on successive nights:
Shailaputri - the daughter of the Himalaya mountain. Holding a trident and a lotus, she rides a bull. She is identified with Sati.
Brahmacharini - greatly devoted to Tapas, she holds a rosary and a water pot. She is said to inspired devotion and is identified with Parvati and Uma.
Chandraghanta - bearing the crescent moon on her forehead, she is of a golden complexion, has three eyes, ten hands, and makes the gesture of being ready for war. She wears a necklace of bells which terrifies demons. She rides a tiger and protects devotees.
Kushmanda - She has eight hands bearing weapons, rides a lion, and is said to be particularly pleased by blood sacrifices.
Skandamata - the mother of Skanda. She is depicted holding Skanda in her lap. She has three eyes, eight hands, wears a large crown, and has been described has having a face composed of eight types of burnished metal.
Katyayini - three-eyed and eight-armed, she is said to be the daughter of the sage Katyayana.
Kalaratri - of dark complexion with dishevelled hair, with a fiery breath, riding a donkey. She grants auspicious boons to devotees and enables them to become fearless. She holds a flaming torch and a cleaver.
Mahagauri - depicted as an innocent young girl of eight years, whose ornaments, garments and complexion are all white. She rides a bull.
Siddhidatri - granter of the eightfold Siddhis and said to be worshipped by all, even Shiva.
In the city of Bhaktapur, Nepal, there is a tradition of masked dancers becoming possessed by the Nine Durgas:
"This tantrically-inspired dance eulogizes Asta Matrika, the eight mother goddesses, who supposedly sit around the city's eight corners to give a watchful guard on it. It is staged all throughout the old city area in turn, which goes from January till June, closely following the lunar calendar. The places and the lunar dates of its staging are specific with no rooms of alteration."
(quoted from: Harmonious hobnobs between heritage and tourism: The success story of Bhaktapur)