Sthala purana of Kamakhya devi:

Gauhati is previously called as Kama rupa, Hari kshetra, Pragjyotisha pura etc.. This is the capital of a demon named, Narakasura.

Lord Vishnu kílled a demon named Hiranyaksha, in the form of Swetha varaha and saved earth. But, it is Tamasika avathara and he couldn’t realise his own state. He married Bhu devi(The Goddess of Earth) and spent life on earth.

One shouldn’t get sexual feelings in the time of Sunset. But, they didn’t followed that rule, which resulted in a son, who is a demon by character. Bhu devi prąyed Lord Vishnu to give boons to her son. Vishnu kept a name, Naraka, and made him as a king to the Pragjyotisha pura. He told to Bhu devi that Naraka becomes very bad and he will be kílled to save the world.
Bhu devi prąyed Vishnu a lot and got a promise from him that Naraka should become immortal unless kílled by her. Vishnu left the form of Varaha and went to Vaikuntha.

Goddess Kamakhya is considered as the Maya rupa of Bhu devi.

Naraka worshiped Goddess Kamakhya and he got a lot of energy. He ruled the world for many Yugas. He captured sixteen thousand princes and enjoying with them against their will. He made friend ship with Banasura. Banasura deviated him from the worship of the Goddess Kamakhya. He told that Kamakhya is also an unmarried girl and Naraka can marry her.

One day night, Naraka observed Goddess Kamakhya dancing in her temple. He approached her and asked to marry him. She laughed at him and told that it will happen if Naraka constructs temple, tank, and stair case from the foot of Nilachal hill to her place, by the end of that night. Naraka got mystic powers by worshiping her. He started fast and almost completed the task. Lord Vishnu appeared in the form a cock(fowl) and crew, which is considered as the starting of the day. Naraka became frustrated, chased and kílled that fowl. In the mean while the day really came. Naraka failed to reach the goal and got angry on Goddess Kamakhya. Kamakhya disappeared from that place.

The incomplete stair case is called as Mekhelauja path.
The place where Naraka kílled the fowl is called as Kukurakata chaki. It is situated in the district of Darrang.

Naraka stealed the Ear rings of Deva matha Adithi(Mother of Lord Indra). This became a very big insult for all gods. At that time Lord Vishnu and Bhu devi incarnated as Sri Krishna and Satya bhama. Indra prąyed Sri Krishna to kíll Narakasura.

Sri Krishna went with Satya bhama to kíll Narakasura. Goddess Kamakhya came with them. Satya bhama didn’t remember Narakasura as her son. Narakasura spoke to her in a very bad way. She became angry and kílled Narakasura by an Astra given by Lord Sri Krishna. All the sixteen thousand princes expressed their desire to marry Sri Krishna. He married all of them. Bhaga datta, the son of Naraka was made as the king of Pragjyotisha pura, by Lord Sri Krishna.