Sources
Encyclopedia of African History: Volume 1, "Egypt: Fatimids, Later: World Trade", available at http://www.bookrags.com/tandf/egypt-fatimids-later-world-trade-tf/
The Islam Project, "Geography and History of the Arabian Peninsula", available at http://www.islamproject.org/muhammad/
muhammad_04_GeographyArabianPeninsula.htm
Sultan Qaboos Cultural Center, "The Indian Ocean in World History Website", available at www.indianoceanhistory.org.
Wilde, Oliver. "The Silk Road". Lecture available at http://www.ess.uci.edu
/~oliver/silk.html#1