Arabic the Youngest Semetic Language with a very poor Textual History, Arabs relied on poetry and Oral Reports

http://www.vistawide.com/arabic/arabic.htm
"Arabic, which was originally a minor language of the Arabian Peninsula, began to spread in the 7th century with the rise of Islam. Apart from being the native language of over 200 million speakers located primarily in Northern Africa and throughout the Middle East, Arabic is therefore also the liturgical language of the vast population of Muslims around the world."

http://www.indiana.edu/~arabic/arabic_history.htm
"The rise of Arabic to the status of a major world language is inextricably intertwined with the rise of Islam as a major world religion. Before the appearance of Islam, Arabic was a minor member of the southern branch of the Semitic language family, used by a small number of largely nomadic tribes in the Arabian peninsula, with an extremely poorly documented textual history."

http://www.alhewar.com/habeeb_salloum_arabic_language.htm
"The Arabic language is the youngest of Semitic idioms which include Aramaic, the Assyro-Babylonian tongues, Ethiopic, Hebrew and South Arabic like Sabean and Himyaritic."

Thus the Arabs used to rely on Oral Reports and Poetry for their genelogies and Lineages (See Tabari Volume 6 Page 38,40) and Al Tabari Volume 9, Page 167 Note 1151), etc.