Kashi Prasad Jayaswal (27 November 1881 – 4 August 1937) was an Indian historian and lawyer. One of the intellectual forces behind the Indian nationalist movement, Jayaswal's works Hindu Polity (1918) and History of India, 150 A.D. to 350 A.D. (1933) are classics of ancient Indian historical literature. Among other things, he is credited with showing that Indian republics, based on the principles of representation and collective decision-making, were among the oldest and most powerful of the ancient world.

A prolific scholar, Jayaswal wrote more than 120 research papers in addition to 11 books and numerous commentaries and translations. He also played a pioneering role in excavating and restoring ancient sites, including the university of Nalanda in modern Bihar. He was also an expert in numismatics, and his discovery of several coins of the Maurya and Gupta periods led to his being the first Indian to be invited to speak at the Royal Asiatic Society of London in 1931.[2] Historian R. C. Majumdar criticized his theories about the Gupta history as "too conjectural and full of wild guesses to be seriously considered".[3]

Jayaswal loved Ramdhari Singh 'Dinkar' like a son and assisted him during the early days of his poetic career.[4][5] His death in 1937 was a blow to the young poet.[5] Much later, he wrote in Kalpna, a magazine published from Hyderabad:

It was a good thing that Jaiswalji was my first admirer. Now when I have savoured the love and encouragement of the Sun, Moon, Varun, Kuber, Indra, Brihaspati, Shachi and Brahmani, it is clear that none of them was like Jaiswalji. As I heard the news of his death, the world became a dark place for me. I did not know what to do."[5] Actually Jaiswalji was the first person to appreciate the historical sense in the poetry of Dinkar.[5]

The K. P. Jayaswal Research Institute in Patna was established by the Government of Bihar in 1950 with the object of promoting "historical research, archaeological excavation and investigations and publication of works of permanent value to scholars".