Europe is a territory considered either as one of the six continents, particularly in the traditional view, or as the western part of Eurasia. In the north it is defined by the Arctic Ocean, in the west by the Atlantic Ocean, in the south by the Mediterranean and Black Seas, as well as the waterways that connect them, and in the east by Asia (there is no consensus on the exact placement of this border). When viewed as a continent, it is the second smallest one and also the second most densely populated. The so-called Western civilization emerged in Europe, and many European nations played a role in world events during the colonial period.