Use the passage below to answer all parts of the question that follows. "Places whose names are all but forgotten once dominated, such as Merv, described by one tenth-century geographer as a "delightful, fine, elegant, brilliant, extensive and pleasant city," and "the mother of the world"; or Rayy, not far from modern Teheran, which to another writer around the same time was so glorious as to be considered "the bridegroom, of the earth" and the world's "most beautiful creation." Dotted across the spine of Asia, these cities were strung like pearls, linking the Pacific to the Mediterranean...
There was good reason why the cultures, cities and peoples who lived along the Silk Roads developed and advanced: as they traded and exchanged ideas, they learnt and borrowed from each other, stimulating further advances in philosophy, the sciences, language and religion. Progress was essential...Leaders in the past understood how important it was to keep up with the times."

Explain ONE specific example of the urbanization described in the first paragraph of then excerpt.