The Princely State of Ramgarh, also known as Ramgarh Raj, was one of the prime Zamindari estates during the rule of the British Empire in India. It was located in the erstwhile Indian province of Bihar. The estate originally was under the administration of the Raja of Chhota Nagpur. Around 1368 AD, the territory experienced disorder for unknown reasons. The brothers Singhdeo and Baghdeo were deputed by the Raja in order to restore order. After the completion of the task, the native ruler did not render the full promised payment. As a result Baghdeo took control over the area after revolting against the ruler and eventually declared himself the Raja of the region, which included the districts of the 24 parganas. At present Ramgarh is located in the state of Jharkhand and is rich in various minerals, such as mica and coal.

Various districts like Bokaro, Koderma and Hazaribagh were included in the area of the princely state. Later Sardar Fateh Singh helped the British administration in the First Sikh War and provided support in the establishment of new authority in the Sutlej districts that were annexed in 1846. He maintained his authority over the administration of the state as and autonomous territory when the sovereign powers of all separate petty states were resumed and were established as Jagirdars.

Rulers of Princely State of Ramgarh
The last ruling chief of the princely state of Ramgarh was Raja Bahadur Kamakshya Narain Singh, who ruled from 1919 to 1947. The ruler of the state acceded to the Government of India in the year 1945. The present titular ruler is Raja Bahadur Saurabh Narain Singh who ascended as the head of the family in 2008.

The chronology of the rulers of the princely state of Ramgarh is mentioned below-
* Raja Baghdeo (1368- 1402)
* Raja Kirat Singh (1402- 1459)
* Raja Ram Singh I (1459- 1537)
* Raja Madho Singh (1537- 1554)
* Raja Jagat Singh (1554- 1604)
* Raja Himmat Singh (1604- 1661)
* Raja Ram Singh II (1661- 1677)
* Raja Dalel Singh (1677- 1724)
* Raja Bishan Singh (1724- 1763)
* Raja Makand Dingh (1763- 1772)
* Raja Bahadur Tej Singh (1772- 1774)
* Raja Bahadur Paras Nath Singh (1774- 1784)
* Raja Bahadur Mani Nath Singh (1784- 1811)
* Raja Bahadur Sidh Nath Singh (1811- 1835)
* Raja Bahadur Lakshmi Nath Singh (1835- 1841)
* Raja Bahadur Shambhu Nath Singh (1841)
* Raja Bahadur Ram Nath Singh (1866)
* Raja Bahadur Trilok Nath Singh (1866)
* Raja Bahadur Nam Narain Singh (1866- 1899)
* Raja Bahadur Ram Narain Singh (1899- 1913)
* Raja Bahadur Lakshmi Narain Singh (1913- 1919)
* Raja Bahadur Kamakhya Narain Singh (1919 - 1970)