[1] Contiguous transcontinental countries are states that have one continuous or immediately-adjacent piece of territory that spans a continental boundary, most commonly the line that separates Asia and Europe.
The lists within this article include entries that meet the following criteria: The boundaries between the continents can be vague and subject to interpretation, making it difficult to conclusively define what counts as a 'transcontinental state'.
In antiquity, Egypt had been considered part of Asia,[citation needed] with the Catabathmus Magnus escarpment taken as the boundary with Africa (Libya).
The conventional Asia-Europe boundary was subject to considerable variation during the 18th and 19th centuries, indicated anywhere between the Don River and the Caucasus to the south or the Ural Mountains to the east.
This area encompasses a large watershed, forest and mountains in the northern portion of Colombia's Chocó Department and Panama's Darién province.