Changes

Although royal roads proved to be useful for military purposes, as armies after the Assyrians began to adopt such roads, it also led to the development of long-distance trade along secure roadways. In part, long-distance roads helped to spawn the developing Silk Road connecting trade between China and Europe (Figure 1). The long-term legacy of royal roads that allowed armies to move quickly were later adopted by various armies.<ref>For more on how long-distance roads benefited trade, see: Bakhtia, L. M., & Bariand, P. (2011). Afghanistan’s blue treasure lapis lazuli.</ref> The modern highway system created in the United States and other countries reflect the concept of rapid movement along large distances by the military, showing that the concepts born in the Iron Age continued to be adopted even by more modern transport. In effect, highways were always seen as initially being for the military above all, but benefits of rapid movement also led to trade thriving along routes, similar to highways today.

==Improvements in Paved Roads==