This book is concerned with the notions of "pidginization" and "creolization" and the role of these processes of language learning in the history of the Arabic language. It is argued that when a new type of Arabic emerged after the Islamic conquests in the 7th century AD, the language went through these processes, as can be concluded from the sociolinguistic context of the period. The radical changes in the language that led to the development of the modern dialects are then seen as the result of pidginization and creolization. Data from the dialects are compared with phenomena in pidginized/creolized languages, and suggestions are given for the application of this framework to the history of other languages.