This paper analyzes economic, political, and cultural legacies of Qusman traders in the port cities of the Arabian Gulf and Indian Ocean. The Qusman (people of al-Qasim, a subregion of Najd) were well known as merchants. This paper traces their commercial activities in the Gulf and Indian ports. While some of them were laborers at the ports and pearl fields, others exported horses and dates from Najd, and pearls from the Gulf to India, and imported rice from India and sugar from Mauritius. They also trafficked slaves and weapons. Qusman traders were also influential politically, socially, and culturally both in these trading centers and back home. This paper discusses how this trade integrated Najd into the global economic system, enabling the two towns of al-Qasim, Buraydah and ‘Unayzah, to become the wealthiest towns in Najd in the 19th and early 20th centuries. Culturally, this paper explains how the two rival towns were cosmopolitan centers surrounded by a desert. Politically, this paper reveals the crucial roles Qusman traders played during the creation period of Saudi Arabia, whether by sending sums to Ibn Saud or by working later as diplomats and representatives for the newly founded state.