Most of the Greek accomplishments in geography were passed on to the Romans. Roman military commanders and administrators used this information to guide the expansion of their Empire. The Romans also made several important additions to geographical knowledge. Strabo(circa 64 BC - 20 AD) wrote a 17 volume series called "Geographia". Strabo claimed to have traveled widely and recorded what he had seen and experienced from a geographical perspective. In his series of books, Strabo describes the cultural geographies of the various societies of people found from Britain to as far east as India, and south to Ethiopia and as far north as Iceland. Strabo also suggested a definition of geography that is quite complementary to the way many human geographers define their discipline today. This definition suggests that the aim of geography was to "describe the known parts of the inhabited world ... to write the assessment of the countries of the world [and] to treat the differences between countries".