As illustration only; a 16th century world map of Qazwini

Ibn Rosteh (903) Kitab al-a'lak an-nafisa

(book of precious stones) from Ispahan (Iran)
Taken from ; Gabriel Ferrand ; Relations des voyages et textes geographiques....
Wiet, Gaston, Ibn Rusteh. Les atours précieux
Also called : Abu Ahmad b. Umar Ibn Rusta or Rustah

Whoever arrives in the land of the Zendjs catches scabies.

In the eastern Indian Sea the inhabited parts are India, Khmer, Zandj, Nadj, and the different people that are part of the Indian people.. ..
About the Indian sea; when the navigator gets into the sea at the gulf of Aden, the first land which he meets is the island of Barbar (Jazira Barbar) which is inhabited by a race of Zandj who are neighbors to the countries of the blacks. It is in that direction that are the lands of Zandjs and Djawaga, as well as all the people that we have talked about, and also others.. .. 

He who wants to go to the land of China (as well as to Zandj) cuts the east of the Indian sea (to go to China) and goes around it till arriving in its western part at the place of the Zandj land that one wants to go to. The one who wants to go to Djawaga goes towards the east till reaching Kalah and from there the land of Djawaga. Only take this road because passing by Djawaga to go to Zandj you have to go through the sea of the dead where the daylight only appears for six hours a day. It is to avoid that that you take to the east in the Indian sea till Kalah, then towards the west of that sea till arriving in the country of the Zandjs.

The two lakes who give birth to the Nile are part of t he torrid regions, as well as the sea of the Zendjs, in which not a single animal can live, because of the high temperature and the density of the water. Really when the sun strikes that sea, it sucks out the sweet water by its heat and so the water becomes heavy and salty………

A merchant has brought from the two seas found behind the land of Kousaniens, that is the sea of the Zendjs, an egg that resembles the ones of ostriches. Except that we have never seen south of the equator any bird like that , and no author has ever mentioned it. One has never seen a single elephant or rhinoceros