Asia is the Earth’s largest and most populous continent, located primarily in the eastern and northern hemispheres. Though it covers only 8.7% of the Earth’s total surface area, it comprises 30% of earth’s land area, and has historically been home to the bulk of the planet’s human population (currently roughly 60%). Asia is notable for not only overall large size and population, but unusually dense and large settlements as well as vast barely populated regions within the continent of 4.4 billion people. Asia has exhibited economic dynamism (particularly East Asia) as well as robust population growth during the 20th century, but overall population growth has since fallen to world average levels. The boundaries of Asia are culturally determined, as there is no clear geographical separation between it and Europe, which together form one continuous landmass called Eurasia. The most commonly accepted boundaries place Asia to the east of the Suez Canal, the Ural River, and the Ural Mountains, and south of the Caucasus Mountains (or the Kuma–Manych Depression) and the Caspian and Black Seas. It is bounded on the east by the Pacific Ocean, on the south by the Indian Ocean and on the north by the Arctic Ocean. Given its size and diversity, the concept of Asia – a name dating back to classical antiquity – may actually have more to do with human geography than physical geography. Asia varies greatly across and within its regions with regard to ethnic groups, cultures, environments, economics, historical ties and government systems.