Tbilisi's favorable trade location, however, did not necessarily bode well for its survival. Located strategically in the heart of the Caucasus between Europe and Asia, Tbilisi became an object of rivalry among the region's various powers such as the Roman Empire, Parthia, Sassanid Persia, Muslim Arabs, the Byzantine Empire, and the Seljuk Turks. The cultural development of the city was somewhat dependent on who ruled the city at various times, although Tbilisi was fairly cosmopolitan.