The Yuezhi were an ancient nomadic people who lived in Central Asia, primarily in the region that is now western China and parts of Afghanistan. They are believed to have originated from the area around the Gansu province and were known for their horse-riding skills and trade activities along the Silk Road. In the 2nd century BCE, the Yuezhi migrated westward due to pressure from the Xiongnu, another nomadic group. They eventually settled in the area of Bactria, where they established the Yuezhi Kingdom and played a significant role in the cultural and economic exchanges between the East and West.