Europe and Asia should actually be considered as one continent. Since much of this combined land area is on the same tectonic plate and no water completely divides Europe and Asia, there really isn’t any reason why they should be considered as two continents other than the stand-by answer of, “That’s how it’s always been.” Many also argue that the cultural differences between those in Europe and those in Asia are significant enough as to create a social divide between the regions even though a physical one may not exist.
How did this view come to be? The earliest known example of Europe and Asia being divided occurred when Greek geographers proposed the division in the sixth century B.C. Their definition of the Europe-Asia dividing line was the Rioni River, which is primarily located in present-day Georgia and originates in the Caucasus Mountains. About 200 years later, the line was judged by most to instead divide present-day Russia along the Don River, which is Europe’s fifth-longest and is located well to the west of the Ural Mountains and very close to where Ukraine sits today.
The dividing line has fluctuated throughout the years since. The most notable change was courtesy of Phillip Johan von Strahlenberg; he moved it further east, to the Volga River and the Ural Mountains. This was done in 1725. However, there are still discussions and disagreements today as far as where the exact Europe-Asia border is although most agree that it crosses Turkey, Georgia, Azerbaijan, Russia and Kazakhstan.
Of course, some stick with the opinion that there is no dividing line and that Europe and Asia are actually part of one continent. This has been becoming more and more true amongst those working in the field of geography although the general public has not completely gotten on board with the idea yet.