Libya officially the Great Socialist People’s Libyan Arab the north, Libya lies between Egypt to the east, Sudan to the southeast, Chad and Niger to the south, and Algeria and Tunisia to the west. With an area of almost 1800000 square kilometres (694984 sq mi), Libya is the fourth largest country in Africa by area, and the 17th largest in the world.The capital, Tripoli, is home to 1.7 million of Libya's 5.7 million people. The three traditional parts of the country are Tripolitania, Fezzan, and Cyrenaica. Libya has the highest HDI in Africa and the fourth highest GDP (PPP) per capita in Africa as of 2009, behind Seychelles, Equatorial Guinea and Gabon. These are largely due to its large petroleum reserves and low population. The flag of Libya consists of a green field with no other characteristics. It is the only national flag in the world with just one color and no design, insignia, or other details. The name in Greek, the tribesmen were called Libues, Latinised to Libyes (with Greek u transcribed as y in Latin). Their country became Libua (or in Classical Attic Libýe with the standard Attic sound change Latinised Libya. But in ancient Greece the term had a broader meaning, encompassing all of North Africa west of Egypt. Later on, at the time of Ibn Khaldun, the same big tribe was known as Lawata. The word jamahiriya , strict transliteration jamahiriyya, which appears in the full title of the country, is an Arabic term generally translated as "state of the masses". It is a neologism, coined by Muammar al-Gaddafi, similar to people's republic.