Rani Sati, also identified as Narayani Devi and referred to as Dadiji (grandmother), is said to be a Rajasthani woman who lived sometime between the 13th and the 17th century and committed sati (self-immolation) on her husband's death. Various temples in Rajasthan and elsewhere are devoted to her worship and to commemorate her act.
When Abhimanyu (the son of the great Pandava, Arjun) died while fighting the battle of Mahabharata, his wife and soon-to-be-mother, Uttara, had wished to commit sati and end her life too. Citing that it would not be appropriate to kill the innocent yet-to-be-born child, Lord Krishna stopped her from doing so. Since she was adamant, He gave her the boon that her desire to become sati shall be fulfilled in the next birth.
Many years later, Uttara was reborn as Narayani bai and Abhimanyu as Tandhan Das. A beautiful horse possessed by Tandhan Das was being eyed by the son of king of Hissar from quite some time. But Tandhan Das refused to part with his precious horse by handing it over to the king’s son. On deciding to obtain forcefully then, the king’s son confronted him. He killed the king’s son in the battle that ensued. This enraged the king and he decided to take revenge soon. Sometime later, Tandhan Das was married to Narayani bai. After marriage, while returning to their village, they were suddenly attacked by the army of Hissar. Tandhan Das fought the battle bravely before he was stabbed in the back and lost his life. The young bride, Narayani bai displayed exemplary courage and bravery by fighting the army singlehandedly and killed the king.
She then asked Ranaji (the caretaker of the horse) to make immediate arrangements for her to be set ablaze along with her husband’s cremation.
Very pleased with Ranaji who played a vital role in fulfilling her wish to be sati with her husband, she blessed him that his name will be taken and worshiped before her name and since then she is known as Rani Sati. Soon after, her influence of 'sat' (truth and loyalty) involuntarily set up the pyre ablaze. A storm rose from the ashes telling Ranaji to take them on the horse and to build a temple wherever the horse stops. The horse stopped in Jhunjhunu where the temple stands today.
The accounts of Rani Sati's life and the events leading to her death vary widely. Her death has been dated to 1295 or 1595 in some re-tellings, while others place her in the 14th century, or even the 17th century. One such legend, recounted by Sakuntala Narsimhan, says:
[Rani] was a seventeen-year-old girl of the Bania caste. The legend is that the nawab coveted the white mare that her betrothed rode on, and in the confrontation that ensued, [Rani's husband] Tandhan Das was killed, leaving his faithful servant as the only survivor apart from Dadi Narayani Devi, and her mare. When the servant asked her whether he should take her back to her father's or to her father-in-law's, she is said to have replied that she would become a sati and wherever the horse stopped while carrying the ashes of the couple, a temple to their memory should be raised.