An Arab is a member of a complexly defined ethnic group who identifies as such on the basis of one or more of either genealogical, political, or linguistic grounds.
The Arabic language and culture began to spread in the Middle East in the 2nd century with genealogically Arab Christians such as the Ghassanids, Lakhmids and Banu Judham. The Arabic language gained importance with rise of Islam in the 7th century AD as the language of the Qur'an, which spread the Arabic language with the early Islamic expansion.
Defining who an Arab is
The definition of an Arab is defined independently of religious identity, and pre-dates the rise of Islam, with historically attested Arab Christian kingdoms and Arab Jewish tribes. The earliest documented use of the word "Arab" as defining a group of people dates from the 9th century BC.  Islamized but non-Arabized peoples, and therefore the majority of the world's Muslims, do not form part of the Arab World, but comprise what is the geographically larger and diverse Muslim World.
In the modern era, defining who is an Arab is done on the grounds of one or more of the following three criteria:
- Genealogical: someone who can trace his or her ancestry to the tribes of Arabia - the original inhabitants of the Arabian Peninsula - and the Syrian Desert. This definition covers fewer self-identified Arabs than not, and was the definition used in medieval times, for example by Ibn Khaldun.
- Linguistic: someone whose first language, and by extension cultural expression, is Arabic, including any of its varieties. This definition covers more than 250 million people. Certain groups that fulfill this criteria, such as many Egyptians, reject this definition on the basis of genealogy.
- Political: in the modern nationalist era, any person who is a citizen of a country where Arabic is either the national language or one of the official languages, or a citizen of a country which may simply be a member of the Arab League and thus having Arabic as an official government language, even if not used by the majority of the population. This definition would cover over 300 million people. It may be the most contested definition as it is the most simplistic one. It would exclude the entire Arab diaspora, but include not only those genealogically Arabs (Gulf Arabs and others, such as Bedouins, where they may exist) and those Arabized-Arab-identified, but also include Arabized non-Arab-identified groups (such as some Maronite Lebanese) and even non-Arabized indigenous ethnicities which may be non-Arabic-speaking, monolingually or otherwise (such as the Berbers in Morocco, Kurds in Iraq, or the Somali majority of Arab League member Somalia).
Syrian Bedouin with family, 1893.The relative importance of these three factors is estimated differently by different groups and frequently disputed. Some combine aspects of each definition, as done by Habib Hassan Touma, who defines an Arab "in the modern sense of the word", as "one who is a national of an Arab state, has command of the Arabic language, and possesses a fundamental knowledge of Arab tradition, that is, of the manners, customs, and political and social systems of the culture." Most people who consider themselves Arab do so based on the overlap of the political and linguistic definitions.
Few people consider themselves Arab based on the political definition without the linguistic one; thus few Kurds and Berbers identify as Arab. But some do, for instance some Berbers also consider themselves Arab (v. e.g. Gellner, Ernest and Micaud, Charles, Eds. Arabs and Berbers: from tribe to nation in North Africa. Lexington: Lexington Books, 1972). Some religious minorities within the Middle East and North Africa who have Arabic or any of its varieties as their primary community language, such as Egyptian Copts, may not identify as Arabs.
The Arab League at its formation in 1946 defined Arab as "a person whose language is Arabic, who lives in an Arabic speaking country, who is in sympathy with the aspirations of the Arabic speaking peoples".
The relation of ʿarab and ʾaʿrāb is complicated further by the notion of "lost Arabs" al-ʿArab al-ba'ida mentioned in the Qur'an as punished for their disbelief. All contemporary Arabs were considered as descended from two ancestors, Qahtan and Adnan.
Versteegh (1997) is uncertain whether to ascribe this distinction to the memory of a real difference of origin of the two groups, but it is certain that the difference was strongly felt in early Islamic times. Even in Islamic Spain there was enmity between the Qays of the northern and the Kalb of the southern group. The so-called Himyarite language described by Al-Hamdani (died 946) appears to be a special case of language contact between the two groups, an originally north Arabic dialect spoken in the south, and influenced by Old South Arabic.
During the Muslim conquests of the seventh and eighth centuries, the Arabs forged an Arab Empire (under the Rashidun and Umayyads, and later the Abbasids) whose borders touched southern France in the west, China in the east, Asia Minor in the north, and the Sudan in the south. This was one of the largest land empires in history. In much of this area, the Arabs spread Islam and the Arabic language (the language of the Qur'an) through conversion and cultural assimilation. Many groups became known as "Arabs" through this process of Arabization rather than through descent. Thus, over time, the term Arab came to carry a broader meaning than the original ethnic term: cultural Arab vs. ethnic Arab. Some native people in Sudan, Morocco and Algeria (Berbers) and in other regions became Arabized.Arab nationalism declares that Arabs are united in a shared history, culture and language. Arab nationalists believe that Arab identity encompasses more than outward physical characteristics, race or religion. A related ideology, Pan-Arabism, calls for all Arab lands to be united as one state. Arab nationalism has often competed for existence with regional nationalism in the Middle East, such as Lebanese and Egyptian.
- Breeding Out the Black Blood -- Why it is impossible.