Before India's independence, Sandur was a princely state, the seat was at the town of Sanduru. The state was founded around 1700 CE by Shrimant Sidalji Ghorpade (died 1715), a Maratha nobleman. In the eighteenth century, the surrounding territory came under the control of the Nizam of Hyderabad. In 1801, Bellary district was transferred to British India, and the rajas of Sandur came under the political authority of the Madras Presidency.
The area of the state was 433 km2. (161 sq. mi.); its population in 1901 was 11,200. The ruler commanded an estimated annual revenue of Rs.3,500/-. The military sanatorium of Ramandrug is located in a range of hills on the western border of the district.
The Raja of Sandur merged his state with the union of India on April 1, 1949. Sandur state was incorporated into Bellary district, then part of the Madras Presidency. In 1953, Bellary District was transferred to Mysore State, which was later renamed Karnataka.