Bibi Raj Kaur was the youngest of Saradar Ran Singh Nakai's children and his only daughter. She had three elder brothers Sardar Bhagwan Singh Nakai, Sardar Gyan Singh Nakai and Khazan Singh Nakai. Their father, a Sandhu Jatt, was a fierce warrior and the third ruler of Nakai Misl. He had fought repeatedly against Kamar Singh, the ruler of Sayyadwala. Sometime before his death in 1781, he defeated him and captured Sayyadwala. Sardar Ran Singh had greatly expanded his Misl's strength so it became dominant among its neighbours. Misl was at its high under Ran Singh it ruled Kasur, Sharakpur, Gugera pargana, and the "Kharral" fort of Kot Kumaliah.