Raja Rai Singh was a prominent ruler of the princely state of Bikaner in Rajasthan, India, during the 16th century. He is known for his contributions to the region's architecture and culture, particularly the construction of the Junagarh Fort, which showcases a blend of Mughal and Rajput styles. Rai Singh was also a skilled military leader and played a significant role in various battles, including those against the Mughal Empire. His reign is remembered for promoting trade and agriculture, which helped enhance the prosperity of Bikaner and its surrounding areas.