Map from around 1860 showing the Gulf of Aden (in German language)
<a href="//commons.wikimedia.org/wiki/August_Heinrich_Petermann" title="August Heinrich Petermann">August Heinrich Petermann</a>
circa 1860 <div style="display: none;">date QS:P,+1860-00-00T00:00:00Z/9,P1480,Q5727902</div>
<a rel="nofollow" class="external text" href="http://www.swan.ac.uk/cds/rd/Somaliland.htm">Somaliland and Aden: Images from the Past</a>