Final answer:
The western portion of the Silk Roads involved the Roman Empire, Parthian Empire, and later the Sassanid Empire, facilitating the exchange of goods and ideas, including the spread of silk to the West and religions such as Buddhism and Islam.
Step-by-step explanation:
While the Han Dynasty interacted with nomadic peoples and controlled the eastern portion of the Silk Roads, the western portion of these trade routes involved other major empires and cultures. The western end of the Silk Roads extended into the Roman Empire, where Chinese silk was prized. Other empires and regions that interacted on the western portion included the various Central Asian states, the Parthian Empire, and later the Sassanid Empire, which lay along the route connecting East to West. These Western territories became crucial in facilitating the exchange of goods, technologies, and ideas that traversed this ancient network.
The Silk Roads thereby connected cultures and empires as disparate as the Roman Empire, the Parthians — who controlled much of Iran and the Middle East prior to the Sassanids — and the nomadic tribes such as the Yuezhi in Bactria, and the Xiongnu. Over time, Arab expansion and the establishment of the Islamic Caliphate would continue this tradition of cultural and commercial exchange. The Silk Roads not only transported goods like silk and spices but also served as veins of cultural exchange, aiding the spread of Buddhism from India to China and eventually contributing to the rise of Islam along these routes.