Complex sentence: The Aussa Sultanate or Afar Sultanate succeeded the earlier Imamate of Aussa, which had come into existence in 1577 when Muhammed Jasa moved his capital from Harar to Aussa with the split of the Adal Sultanate into Aussa and the Harari city-state.
Split into simpler sentences: The Aussa Sultanate or Afar Sultanate succeeded the earlier Imamate of Aussa. The latter polity had come into existence in 1577 when Muhammed Jasa moved his capital from Harar to Aussa with the split of the Adal Sultanate into Aussa and the Harari city-state.