Europe is considered a separate continent from Asia because of its distinct historical, cultural and political identity, rather than any clear geographical demarcation.
Eurasia forms one single landmass, therefore, the debate on why Europe should be considered a separate continent from Asia has been going on for a long time. The Greek mariners in the 6th century B.C. were the first to name and map land and sea navigational routes, and were also the first to name the two continents. Since that time till now, geographers have failed to come to a clear conclusion on what really separates Europe from Asia.
There have been attempts at defining physical boundaries following the Ural mountain watershed as the separating physical feature between the two continents, but the path followed by the Ural river that flows into the Caspian sea has been unclear for demarcation.
Attempts at using the Caspian sea as a demarcation have also been inconclusive due to the ambiguity regarding Georgia, since it could be interpreted as being part of either continent. Cyprus is another country whose location is a subject of interpretation on whether it is part of Europe or Asia. A large part of Turkey lies in Asia, however, culturally and politically, it has been closer to Europe and therefore sees itself as a European country.
Identifying the dividing line between continents on geographical lines is ambiguous and therefore, the subject of Europe as a separate continent from Asia is left to historical, cultural and political identity. Based on this, most present day geographers have largely agreed that Europe and Asia are separate continents though they remain part of a single landmass.
The definition of a continent is itself a matter of interpretation and debate and finding consensus between geographers to arrive at a clear definition has remained elusive. In the meanwhile, Europe and Asia remain separate continents.