Seven divine maathrikes who had been living their immortal lives in Varanasi came floating southward a great many ages ago, and paused over Hassan. In those days when the western ghats were pure jungle and Hassan was a mere small habitation a short distance from the hills, on jungly plains, what lay below bewitched the divine ladies, and they landed softly in town. Seeing how it was beautiful even up close, they decided they must live forever there. For the divine, forever is truly forever, and the maathrikes live in Hassan even now.
Of the seven, three maathrikes (mothers) chose for their new home an anthill. They were Vaishnavi, Kumari, and Maheshwari. Three others chose three wells in a pond a short distance from the anthill, which pond came to be called Devigere, the pond of the goddesses. They were Varaahi, Indrani and Chamundi. The seventh among them, Brahmi Devi, went some distance south-west of the other six, and settled on top of a short hill, and a village grew round it, and took one of her several names, Kenchamma, and became Kenchammana Hosakote, or Kenchamma's new fort. Why did they call her Kenchamma? Or Kenchamba? Because of a blush on her cheeks? Because of red in her hair? Or red the color of blood of the rakshasa with whom she fought a long and bloody battle and slayed him there? And, coming back to Hassan, who among the three—Vaishnavi, Kaumaari, Maheshwari—is Hasanamba? I'm going to find out on my next visit, later this month.
A story on the Internet says Malik Kafur, Alauddin Khilji's general who pillaged the Dwarasamudra (Halebid) Temple of the Hoysalas thirty kilometers from the town-center of modern Hassan, was resting his troops somewhere in Hassan. His men cooked a meal of meat and consumed it near the anthills where the devis had by now been long in residence, and so angered the devis that in consequence his troops began to fall dead a man at a time. A stricken Kafur quickly met the priests of the devis but they couldn't help him, the affront on the devis being so terrible. But Hasanamba, who is God to all men and forgives every penitent, appeared to Kafur in a dream and suggested he build a temple to her, which he did using local expertise, and earned forgiveness, and thereafter continued his campaign and celebrated great victories.
(This account needs adjustment with another, that Krishnappa Nayaka, a palegaar (chieftain) of the place in the twelfth century, was who really built the temple. Maybe the one made better what another had built. Perhaps not. Does it matter, so long as the stories live and regenerate into livelier ones?)
Once the temple was ready, the devi ordered that it be opened for darshan only once in a year, during the lunar month of Ashwayuj. And she made the temple powerful with miracles: Three female faces formed over the anthill in the core of the temple, and the anthill became the chief deity. A big round red chandan formed on the foreheads of the devis, which the priests scrape out on the day they close the temple for the year, but the devis form the chandan again upon their forehead when the temple is opened. The nandaa deepa, (a ghee-lit lamp) burns all year round, for the entire duration when the temple doors are shut, with the ghee never depleting. And the anna naivedya (the rice offering) submitted before the devi at the time of closing the temple is warm and unspoiled when the doors are opened again. For centuries now, Hindus who have a connection to Hassan have lived in faith in these miracles which only a privileged few get to witness on the day on which the temple re-opens in the year: the temple authorities, and the District Commissioner, and a few others deemed important. People come in hundreds of thousands, as they've done for centuries now, to say thanks for prayers answered, and with fresh prayers for new needs and new problems.