The word Arab means clear, as in logical rather than as in pure. Bedouin elders still use this term with the same meaning "those whose speech they understand they call Arab" and those whose speech is of unknown meaning to them they call Ajam or Ajami. In the Persian Gulf region the term Ajam is often used to refer to the Persians.
The "original Arabs" of South Arabia, descending from Qahtan. The Qahtanites are said to have migrated the land of Yemen following the destruction of the Dam of Marib. The Qahtanite arabs were responsible for the ancient civilizations of Yemen including the biblically renowned Sheba (a descendent of Qahtan). The "Arabized Arabs" of North Arabia, descending from Adnan supposed to be a descendant of Ishmael through Kedar. The Arabic language as it is spoken today in its classical Quranic form was the result of a mix between the original Arabic tongue of Qahtan and the northern Arabic which borrowed from other northern Semitic languages from the Levant. An Arab is 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.
An Arab in the contemporary sense of the word is one who is a national of an Arab state with a command on the Arabic language and possesses a fundamental knowledge of Arabian tradition that is of the manners, customs and political and social systems of the culture. In that order many groups came to be known as "Arabs" not through descent but through Arabisation. Thus over time the phrase Arab came to take a broader meaning than the unique cultural term. Many Arabs live in Sudan, Morocco, Algeria and elsewhere became Arab through cultural transmission.