This book is part of a historiographic movement on inter-Maghreb relations that has been underway for about ten years. In Maghrebian universities, seminars, colloquia and publications are multiplying and diversifying. This book traces in an analytical way certain aspects of the common history of Algeria and Morocco, in particular the evolution of the migration of Algerian Muslim and Jewish populations to Morocco during the Ottoman period (1517-1830) and the colonial period (1830-1962). It also tries to provide elements of explanation highlighting the importance of building a Maghreb Union taking into account the potential of this region. This Union remains undoubtedly a decisive factor to establish the free movement of people and goods through open land borders in a Maghreb without borders.