Europe is most commonly considered to be separated from Asia by the watershed divides of the Ural and Caucasus Mountains, the Ural River, the Caspian and Black Seas and the waterways of the Turkish Straits. Although the term “continent” implies physical geography, the land border is somewhat arbitrary and has been redefined several times since its first conception in classical antiquity. The division of Eurasia into two continents reflects East-West cultural, linguistic and ethnic differences which vary on a spectrum rather than with a sharp dividing line. The geographic border between Europe and Asia does not follow any state boundaries: Turkey, Russia, Azerbaijan, Georgia and Kazakhstan are transcontinental countries. European countries like Italy, Portugal, Spain, France, United Kingdom and Netherlands are also transcontinental countries, having their main territory in Europe, and other small territories spread across different continents.