The World map of the Caliph Al-Ma'mun
Taken from : catalogue Library of Congress (map found on several websites)
As contained in the Kitab masalik al-absar by Ibn Fadlallah al-Umari (d. 1349 A.D.), MS 2797/1 Ahmet III Collection, Topkappi Sarayi Library, Istanbul. Includes ancillary reconstruction of the facsimile map by Dr. Aladdin Jokhosha. In this same work are also found the different sectional maps. Added is the map for East Africa.
The East African section of this map
-Black area: Knowledge from the Indonesian sailors at this moment immigrating to Madagascar. South-East Asia mainland and islands are clearly recognisable. As well as the free ocean all the way to the coast of Africa. (Not so in the Ptolemy map).
-Green area: Pure copy from Ptolemy. Comparison with the same area from the oldest surviving map of Ptolemy. (From about 1200 found at Vatopedi monastery library on mount Athos).
-Red area: Mixed; Arabic, Indonesian, Ptolemy.
Also a second Horn of Africa appears. (Source unknown).
In subsequent maps influenced by this one; the first horn of Africa will slowly disappear and the new one will be disproportionally far from Aden in Arabia.