Wikipedia
Kalbhor is the surname of the people belonging to 96 Kuli Maratha caste of Hindus in India. Their ancestors originated in Rajasthan and had the surname of "Chauhan". They migrated after a war between Rajputs and Mughals and settled in various parts of the country in order to protect themselves.
In the 14th century, the Chauhans settled in a village called Loni(now known as Loni Kalbhor), east of Pune. Their basic profession is farming. In the 15th century, a farmer in Loni found a statue of the goddess, Kaalbhairavi, which was assumed to be a blessing from the goddess and the people started using a new surname, "Kalbhor". Besides Loni, Kalbhors have now been localized in places such as Pimpri-Chinchwad(Kalbhor Nagar), Nigdi, Akurdi and Pali. And even some of the kalbhor's are located near Karad.
In Ranjit Desai's book on Shivaji, 'Shriman Yogi', the reference to Pandits from Pali with surname Kalbhor is mentioned, which cites the existence of Kalbhors in Pali in the 17th century.