Japan (Japanese: 日本, Nippon [ɲippoꜜɴ] (About this soundlisten) or Nihon [ɲihoꜜɴ] (About this soundlisten); officially 日本国, About this soundNippon-koku or Nihon-koku) is an island country located in East Asia. It is bordered by the Sea of Japan to the west and the Pacific Ocean to the east, and spans from the Sea of Okhotsk in the north to the East China Sea and Philippine Sea in the south. Part of the Pacific Ring of Fire, Japan encompasses an archipelago of about 6,852 islands, with five main islands (Hokkaido, Honshu, Kyushu, Shikoku, and Okinawa) comprising 97% of the country's area. Japan is divided into 47 prefectures and traditionally into eight regions. Approximately two-thirds of the country's terrain is mountainous and heavily forested, and less than one-eighth of its land is suitable for agriculture. Consequently, Japan is among the most densely populated and urbanized countries in the world. The largest urban area is the metropolitan area centered on the capital city of Tokyo, which is the most populous in the world . Japan itself is the world's eleventh most populous country. The kanji that make up the name of Japan mean "sun origin"; in the Western world, the country is often known by the sobriquet "Land of the Rising Sun". While archaeological evidence indicates that Japan was inhabited as early as the Upper Paleolithic period, the first written mention of the archipelago appears in Chinese texts from the first century AD. Between the fourth and ninth centuries, the kingdoms of Japan gradually unified under an Emperor and imperial court based in Heian-kyō (modern Kyoto). However, beginning in the twelfth century, de facto political power came to be held by a succession of military dictators (shōgun) and feudal lords (daimyō) and enforced by a class of warrior nobility known as samurai. After a century-long period of civil war, Japan was reunified in 1603 under the rule of the Tokugawa shogunate, which enacted a policy of isolationism. This period ended in 1853 when a United States fleet forced Japan to open to the West, leading to the fall of the shogunate and the restoration of imperial power in 1868. In the following Meiji era, Japan adopted a Western-style government and pursued a program of industrialization and modernization; this transformed the feudal society into a great power, with Japan establishing a colonial empire in East Asia after decisive victories in the First Sino-Japanese War and Russo-Japanese War. In 1937, the Empire of Japan invaded China, beginning the Second Sino-Japanese War; in 1940, it signed the Tripartite Pact and entered World War II the following year on the side of the Axis powers. After suffering major defeats in the Pacific and two atomic bombings, Japan surrendered to the Allies in 1945, coming under a brief occupation and adopting a new post-war constitution. Japan has since maintained a unitary parliamentary constitutional monarchy with the Emperor as a ceremonial head of state and an elected legislature known as the National Diet. Today, Japan is a member of the United Nations, the OECD, the G7, and the G20. Although it has officially renounced its right to declare war, Japan maintains a modern military for peacekeeping and self-defense, which has been ranked as the world's fourth most powerful. Following World War II, Japan experienced record economic growth to become the world's second-largest economy by 1980. Today, Japan's economy is the world's third-largest by nominal GDP and fourth-largest by purchasing power parity; it is also the fourth-largest importer and exporter and a global leader in the automotive and electronics industries. Japan is ranked "very high" on the Human Development Index; its population enjoys high levels of education and the second-highest life expectancy in the world, though it currently is experiencing a projected decline due to low birth rates. Culturally, Japan is renowned for its art, cuisine, literature, cinema, music, and popular culture.