The Arab world ( ; formally: ), also known as the Arab Nation ( ), consists of the 23 Arabic-speaking countries of the Arab League. The standard definition of the Arab world comprises the 23 countries and territories of the Arab League, an area stretching from the Atlantic Ocean in the west to the Arabian Sea in the east, and from the Mediterranean Sea in the north to the Horn of Africa and the Indian Ocean in the southeast. It has a combined population of around 422 million people, with over half under 25 years of age. The sentiment of Arab nationalism arose in the second half of the 19th century along with other nationalist movements within the Ottoman Empire. The Arab League was formed in 1945 to represent the interests of the Arabs, and especially to pursue the political unification of the Arab countries, a project known as Pan-Arabism. The term “Arab world” is usually rejected by those who live in the region but do not consider themselves Arabs—such as Berbers, Iranians, and Kurds—as it implies the entire region is Arab in its identity, population, and origin, whereas the original homeland of the Arabs is the Arabian Peninsula. The term is also rejected by some indigenous Semitic minorities such as the Assyrians, and many of Maronites and Copts, as they pre-date Arabs in North Africa, Mesopotamia and the Eastern Mediterranean.