The reopening of the Mediterranean routes in the tenth century sparked, in some regions of Europe, a long period of economic boom. It also triggered a social change whereby some members of the nobility, despite their social status, turned to commerce. I explain these events through the lens a Kiyotaki and Wright (1989) model, extended to a two-country world. The response of the elite to a communication shock causes the economy to transit from a low-to a high-production equilibrium, if pre-existing class differences are not too large. Quantitative experiments illustrate the view of economic historians that medieval expansion ensued in regions where the elite enjoyed relatively modest privileges and was slow in places, most notably France, where the elite's preoccupation for preserving the social-status was strong.

十世纪地中海路线的重新开放引发了欧洲某些地区的长期经济繁荣。它还引发了社会变革，一些贵族成员尽管拥有社会地位，却转向了商业。我通过Kiyotaki and Wright（1989）模型的镜头解释了这些事件，这种模型扩展到了两个国家的世界。如果先前存在的阶级差异不太大，那么精英对沟通冲击的反应会导致经济从低生产率向高生产率的平衡过渡。定量实验说明了经济史学家的观点，即中世纪的扩张发生在精英阶层享有相对较弱的特权并且在某些地方发展缓慢的地区，最显着的是法国，那里的精英阶层对于保持社会地位的关注度很高。