Fez
The great city of Morocco, which Ibn Khaldun names with Cairo as crowded cities where deaths were most frequent.
Today: Fes, Morocco
As If the Whole World Had Changed
Ibn Khaldun, the Muqaddimah (Introduction to History), 1377 · 1377, revised later (the plague of 1348–1349)
وسبب كثرة العفن والرطوبات الفاسدة في هذا كله كثرة العمران ووفوره آخر الدولة لما كان في أوائلها من حسن الملكة ورفقها وقلة المغرم وهو ظاهر ولهذا تبين في موضعه من الحكمة أن تخلل الخلاء والقفر بين العمران ضروري ليكون تموج الهواء يذهب بما يحصل في الهواء من الفساد والعفن بمخالطة الحيوانات ويأتي بالهواء الصحيح ولهذا أيضا فإن الموتان يكون في المدن الموفورة العمران أكثر من غيرها بكثير كمصر بالمشرق وفاس بالمغرب والله يقدر ما يشاء
The cause of so much rot and foul moisture in all this is the large population at the end of a dynasty. It grew because the dynasty, in its early days, ruled well and gently and taxed lightly. This is plain. For this reason, as is shown in its place in philosophy, there must be empty space and open country between settlements. Then the movement of the air can carry off the corruption and rot that living things give to the air, and bring in healthy air. This is also why deaths are far more frequent in crowded cities than elsewhere, as in Cairo in the East and Fez in the Maghrib. God decrees what he wills.