THE SPREAD OF ISLAM: New evidence of the role of trade and geographical inequality

Islam flourished in very challenging geographical terrains – parts of the world that harboured inherently unequal economic opportunities and often bred conflict. Any political platform that attempted to bring clashing populations together had to address these primordial inequities. Islam was certainly such a movement – and its spread is a prime example of how geography shapes a society’s institutional and social arrangements.

These are among the findings of research by Stelios Michalopoulos, Alireza Naghavi and Giovanni Prarolo, published in the December 2018 issue of The Economic Journal. Their study seeks to explain the contemporary spatial distribution of Muslim communities worldwide:

  • First, they demonstrate the role that ancient, pre-Islamic trade routes have played in facilitating the spread of Islam.
  • Second, they uncover how a region’s ecological similarity to the Arabian peninsula predicts the presence of Muslim communities today.

Motivated by numerous case studies on the historical relationship between trade and Islam, the researchers construct detailed data on pre-Islamic trade routes, ports and harbours. In the first contribution of their study, they establish that proximity to the pre-600 CE trade network is a significant predictor of today’s Muslim adherence in the Old World.

The researchers conduct the analysis both across and within countries. Leveraging within contemporary-states-across-group variation in religious composition is desirable from an empirical point of view as country-level features, including the current-day political boundaries and state-wide religious policies, have arguably influenced the observed cross-country variation in Muslim adherence.

These empirical findings complement a rich body of qualitative work by prominent Islamicists who have extensively discussed the role of long-distance trade, noting both the diffusion of Islam along trade routes and the importance that Islamic scriptures confer on trade-related matters.

An innovation of Islam was the practice of direct trade, in which Muslim merchants personally carried goods over long distances along the trade routes rather than relying on intermediaries. For example, the acceptance of Islam in most of inner Asia, Southeast Asia and sub-Saharan Africa is known to have occurred primarily through contacts with Muslim merchants.

In addition, the highly personal practice of exchange created preference for Muslims to conduct trade with co-religionists. Therefore, merchants who converted to Islam enjoyed substantial externalities, such as access to the Muslim trade network, steady trade flows and a reduction in transaction costs.

The second contribution of the new study is to explore whether a region’s ecological similarity to the Arabian peninsula predicts the presence of Muslim communities.

But which are the salient geographic features of the cradle of Islam? The Arabian peninsula has a distinct geography, mainly consisting of desert and semi-arid landscapes with few pockets of moderate fertility, including today’s Yemen and scattered oases in the interior.

To capture this distinct landscape, the study constructs for each country/ethnic homeland the Gini coefficient of land quality for agriculture. The researchers uncover the fact that ecological similarity to the Arabian peninsula (reflected in the degree of inequality in the potential for farming across regions) increases Muslim representation.

But why does a region’s ecological similarity to the Arabian peninsula matter for the spread of Islam? The researchers discuss various explanations that may rationalise this pattern, which they have documented first time.

They start by establishing that groups residing along geographically unequal territories have a particular production structure (both historically and today) with pasture dominating the semi-arid landscapes and farming taking place in the few relatively fertile regions. These stark differences in the underlying productive endowments generate incentives to trade but may also lead to conflict.

Both instances abound in the historical record. For example, Ibn Khaldun (1377), one of the greatest philosophers of the Muslim world, observed that a crucial factor for understanding Muslim history is the central social conflict between the primitive Bedouin and the urban society (‘town’ versus ‘desert’).

Similarly, contemporary scholars have noted that when farmers and herders co-existed in the absence of an institutional framework coordinating their activities, their interactions were often conflictual, disrupting trade flows across these territories.

The authors conjecture that the trade-promoting Islamic institutional package with its redistributive economic principles, initially engineered to gain a hearing across tribes residing in the geographically unequal regions of the Arabian peninsula, was likely to be adopted across similarly challenging geographies.

Trade and Geography in the Spread of Islam’ by Stelios Michalopoulos, Alireza Naghavi and Giovanni Prarolo

In a related study published in 2016, the authors explore how the endogenous adoption of economic principles similar to those found in Islam shaped the economic performance of Muslim societies across different stages of development: ‘Islam, Inequality, and Pre-Industrial Comparative Development’ by Stelios Michalopoulos, Alireza Naghavi and Giovanni Prarolo, Journal of Development Economics 120: 86-98.

Their research is also reported at voxeu