奄蔡（Alans，或 Alani，也拼为 Alauni 或 Halani）为古代中亚印欧语系游牧民族，又作阖苏，1—3世纪中叶的 东汉三国时期也称阿兰聊或阿兰。他们族源是塞克人—萨尔马特人。

古希腊罗马文献中称之为Aorsoi、Alanorsi。奄蔡首次见于《太史公书·大宛列传》。西汉时期，该民族在锡尔河与阿姆河之间的中亚河中地区的锡尔河以北的康居（咸海）西北、里海北部的草原游牧，东汉时期隶属康居。后因为在158年一小支北匈奴西迁，奄蔡也随之逐渐西迁，其中一部分随着巴兰姆伯尔大单于去了欧洲（374年），在伏尔加河与顿河之间地区定居，另一部分则留在高加索以北地区。

The Alans (or Alani) were an Iranian nomadic pastoral people of antiquity.

The name Alan is an Iranian dialectical form of Aryan, a common self-designation of the Indo-Iranians. Possibly related to the Massagetae, the Alans have been connected by modern historians with the Central Asian Yancai and Aorsi of Chinese and Roman sources respectively. Having migrated westwards and become dominant among the Sarmatians on the Pontic Steppe, they are mentioned by Persian and Roman sources in the 1st century AD. At the time they had settled the region north of the Black Sea, and frequently raided the Parthian Empire and the Caucasian provinces of the Roman Empire. In 215-250 AD their power on the Pontic Steppe was broken by the Goths.