Kalapahad or Kala Pahar (Black Mountain) was the title of a Muslim general of Mughal governor Sultan Sulaiman Karrani of Bengal. According to some historical documents he was Rajiv Lochan Ray or Kalachand Roy Bhadury a Bengali (Barendra Brahmin) General of Gour Sultanate, converted to Islam. After conversion to Islam he became Muhammad Farmuli, but is popularly known as Kalapahad. He was instrumental in conquering parts of Odisha for the Afghans of Bengal. Bangladeshi scholar Ghulam Murshid has said that the figure of Kalapahad is largely fictional.
After the defeat in the Battle of Tribeni, Sulaiman Karrani was forced to make peace. He realized that he would never be able to conquer Bhurishrestha unless he could defeat Rajiv Lochan Ray. Sulaiman Karrani invited Rajiv Lochan Ray for negotiations in his palace. Rajiv Lochan Ray met and fell in love with the daughter of Sulaiman Karrani and willingly converted to Islam. According to other sources, Sulaiman Karrani planned to have Rajiv or Kalachand fall in love with beautiful and charming daughter by including her in meetings and feasts with him. He offered Rajiv Lochan Ray to convert to Islam to which he offered to convert his daughter to Hinduism and marry her. However, contemporary Hindu scholars opposed to such a matrimonial alliance and decreed that conversion to Hinduism was illegal. Enraged, Rajiv Lochan Ray converted and married Karrani's daughter taking the name of Kalapahad (Black Hill - the destroyer). He led Karrani's revenge over Mukundadeva and attacked Odisha. He defeated Mukundadeva and sacked major towns and religious places of Odisha including Hijli, Cuttack, Jajpur, Sambalpur, Konark, Ekamrakhsetra, Puri etc. in 1568. It alleged that he forcefully converted thousands and of Hindus into Muslims and terrorised the undivided Bengal, Bihar and Orissa by Destroying many temples and Hindu deities as revenge.