The spread of Islam, particularly in Africa and Asia, owes much to the trade of goods such as spices and gold, and slaves as well. The benefits of being in alliance with the extremely powerful and profitable Muslim traders was a catalyst for rulers and merchants to convert to the religion, which often favored Muslim traders over those of other faiths. The spread of Islam was slow and took hundreds of years, however many of the areas where people converted still are Islamic strongholds today.
The central location of early Islamic regions -- between Europe, Asia and Africa -- allowed the Arab world to have great control over trade routes. A prime example of the spread of Islam through trade is seen with the spice trade, which was largely in Muslim hands, as the routes between Asia, Africa and Europe passed through Arab and African Muslim lands. The portability of spices, along with their usefulness in everything from food and medicine to incense, made them important items of trade. The Muslim practice of direct trade offered further exposure to the religion: Rather than working through intermediaries, Muslim merchants would travel to the trading destinations, thus allowing exposure to the religion within other countries as well.
Spread to Africa
Islam spread early to Africa, initially by way of Egypt, which operated as a gateway between the Arab and African worlds. In Eastern Africa, Muslim traders arrived in present day Sudan, where many rulers converted because of the benefits they received by allying themselves with the well-off traders. As the Muslim traders went south, they began to marry the higher class women of coastal cities, which brought important trade alliances and a sense of unity to the upper class, consequently establishing Islam as the religion of the elite. Through trade in western Africa, Arab and Muslim traditions became heavily ingrained in the Maghreb -- now Tunisia, Algeria and Morocco. Salt and gold attracted traders to the western Sub-Saharan region, where merchants were able to convince the leaders of the virtues of Islam by way of their respected advice on trade and governing. Ghana was a focus of much of the trade in the West, and rulers converted to Islam to show good will towards the northern countries they needed for horses and tax money.
Spread to Asia
Many areas in Asia, such as those on the Silk Road or in Central Asia, conversions were primarily a result of the beneficial economic policies offered by Islamic leaders. Even among the conquered people in Central Asia, Islam continued to spread without force as traders brought the religion north and west. Conquered people along the Silk Road were not always forced to convert to Islam, however many did due to financial considerations. Since Muslim merchants worked together, those who converted to Islam were able to gain valuable contacts to help expand their trade. Laws governing economic affairs also favored Muslims over non-Muslims, adding another benefit for merchants and traders to convert.
In Southeast Asia, an area with a high Muslim population today, Islam spread through trade between India and Arabia. Similar to places in Africa, leaders of the coastal towns were one of the first to convert, as they were influenced by merchants who set up businesses in the area. Eventually inland areas began to turn Muslim in an effort to increase trade with the more prosperous coastal cities.
The European Slave Trade
Although trade of goods was an important factor in the spread of Islam throughout Africa and Asia, the European slave trade was important as well, particularly in the southern region of Africa, and South Africa specifically. In the 17th century, the Dutch began to import Muslim slaves from their colonies in Southeast Asia to their colonies in southern Africa in order to work their farms. During the 18th and 19th centuries, England recruited Hindu and Muslim Indians to work their sugar cane plantations in South Africa, although these people generally were paid a small wage. Of the slaves brought to the Americas, 15 to 20 percent were Muslim, and some aspects of their Muslim faith were retained in songs and names, among other traditional ways of life.