Asia is the world's largest continent by extension, and is often considered a single macro-continent together with Europe, known as Eurasia. Among all continents, it has the greatest ethnic, geographical and environmental diversity, as well as being the most populous. It also has the two most populous countries in the world, China and India, in addition to numerous other nations with populations over 100 million inhabitants (Japan, Pakistan, Bangladesh, Indonesia). China, India and Japan represent the modern day incarnations of ancient civilizations, while Russia also has strong interests in Asia, having a large part of its territory in the continent. The south-east part of Asia is considered, on a systemic level, similar to the Middle East. Asia is banked to the south by the Indian Ocean and to the east by the Pacific Ocean, and due to its acquired strategic and economic importance, has become central in the new modern world.