Building concepts and traditions of Islam came gradually with trade and proselytizing. The formation of Islam and Islamic societies in western Africa was not done by conquest or force, but in a gradual, non-disruptive way. The migration of Muslim merchants, proselytizing of scholars and teachers, and the interaction between Muslims and non-Muslims through trade facilitated this peaceful change and led to the eventual conversion of a vast portion of W. African inhabitants. By the tenth and eleventh centuries, many of the “Sudanic States” such Mali and Ghana had gained their “Islamic identity” through the conversions of their rulers.