Sarahan was the capital of rulers of former Bushahr State. Bushahr dynasty earlier used to control the state from Kamroo. The capital of state later was shifted to Sonitpur. Later Raja Ram Singh made Rampur as the capital. It is believed that the country of Kinnaur was the Kailash mentioned in Puranas, the abode of Shiva. With its capital at Sonitpur this former princely state was extended up to the entire area of Kinnaur where for sometimes Shiva disguised himself as Kirata. Today, the then Sonitpur is known as Sarahan. Banasura, the ardent devotee of Lord Siva, eldest among the one hundred sons of great ablative demon King Bali and the great-grandson of Vishnu votary Prahlad, during the Puranic age was the ruler of this princely state.