The Hajj moved merchants, scholars, and slaves across the Islamic world annually

Evidence

This degree of physical mobility, without parallel in pre-modern societies, involves important social, intellectual and economic consequences. The pilgrim, if wealthy, may be accompanied by slaves, some of whom he sells on the way to pay the expenses of his journey. If he is a merchant, he may combine his pil­ grimage with a business trip, buying and selling commodities in the places through which he travels, and thus learning to know the products, markets, merchants, customs and practices of many lands. If he is a scholar, he may take the opportunity to attend lectures, meet colleagues, and acquire books, thus participating in the diffusion and exchange of knowledge and ideas. — Bernard Lewis, From Babel to Dragomans, 729

Categorization

• XREF: Reframes the pilgrimage as an infrastructure institution analogous to how pre-modern trade fairs functioned in the law-merchant literature already in the cluster.
• ADDENDUM: Provides a non-Western, religious case of long-distance mobility and infrastructure that parallels the communication/trade-network material in the knowledge-production cluster.