“平夷” is just a name of a county. It is a proper noun。 "晋永嘉五年(311年) 分牂柯置平夷郡。" In Yong Jia 5th Year of Jin (AD 311), a part of tthe Zang Ke (牂柯) Region was separated and became a new Region named Ping Yi (平夷). "治所平夷县(在今贵州仁怀县西南)。" The seat of its local government is in Ping Yi County, which located in today's southwestern part to Ren Huai County, Gui Zhou Province. "领平夷、鄨两县。" Two counties are under the jurisdiction of Ping Yi Region: the Ping Yi County and the Bi County