Samudragupta's empire included a core territory in northern India. It was directly controlled by the emperor. Besides, it included some monarchical and tribal tributary states. Historian R. C. Majumdar theorizes that Samudragupta directly controlled an area extending from the Ravi River (Punjab) in the west to the Brahmaputra River (Bengal and Assam) in the east, and from the Himalayan foothills in the north to the Vindhya hills in the south. The south-western boundary of his territory roughly followed a line drawn from present-day Karnal to Bhilsa.