The expansion of Scythian cultures, stretching from the Hungarian plain and the Carpathian Mountains to the Chinese Kansu Corridor, and linking the Middle East with Northern India and the Punjab, undoubtedly played an important role in the development of the Silk Road. Scythians accompanied the Assyrian Esarhaddon on his invasion of Egypt, and their distinctive triangular arrowheads have been found as far south as Aswan. These nomadic peoples were dependent upon neighbouring settled populations for a number of important technologies, and in addition to raiding vulnerable settlements for these commodities, they also encouraged long-distance merchants as a source of income through the enforced payment of tariffs. Sogdians played a major role in facilitating trade between China and Central Asia along the Silk Roads as late as the 10th century, their language serving as a "lingua franca" for Asian trade as far back as the 4th century.