What is "yancai"

Yancai was the Chinese name of an ancient nomadic state centered near the Aral Sea during the Han dynasty period (206 BC - 220 AD). They are generally considered to have been an Iranian people of the Sarmatian group. After becoming vassals of the Kangju in the 1st century BC, Yancai became known as Alanliao . Yancai is often connected to the Aorsi of Roman records, while Alanliao has been connected to the later Alans.