By then, nomads were being eclipsed by professional merchants who traveled the Silk Roads, often making huge profits. But those cities that had been founded by nomadic peoples became hugely important. They continued to grow because most of the trade on the Silk Road was by caravan, and those caravans had to stop frequently, you know, for like food and water and prostitutes. These towns became fantastically wealthy. One, Palmyra, was particularly important because all of the incense and silk that traveled to Rome had to go through Palmyra. Silk was so popular among the Roman elite that the Roman Senate repeatedly tried to ban it, complaining about trade imbalances caused by the silk trade and also that silk was inadequately modest. To quote Seneca the Younger, I see clothes of silk if materials that do not hide the body, nor even one's decency, can be called clothes.