But when Rome collapsed in the fifth century and the Middle Ages began, direct trade of spices stopped, and so did that kind of hands-on knowledge of travel and geography.

但到了5世纪，罗马帝国崩塌了，中世纪开始了，香料直接贸易停止了，所以人们对于香料的运输和来源地的直接认识也就中断了。

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Dependence on long-distance trade also meant that the great empires of the Middle East were built both literally and figuratively on shifting sand.

对长途贸易的依赖也意味着，伟大的中东帝国无论是实际上还是象征意义上，都是建立在流沙之上的。

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Trade was the mainstay of the urban economy in the Middle East, as caravans negotiated the surrounding desert, restricted only by access to water and by mountain ranges.

因为商队只能通过水路和山脉进入沙漠，贸易就成为了中东城市的主要经济支柱。

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So increasingly now, Africa, Middle East, all the way over to India and then to China, huge trade routes, huge investment routes.

趋势越来越明显，非洲，中东地区，一直往东到印度再到中国，一条巨大的商业渠道，巨大的投资线路。

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