The Huns were a nomadic people who lived in Central Asia, the Caucasus, and Eastern Europe between the 4th and 6th centuries AD. According to European tradition, they were first reported living east of the Volga River, in an area that was part of Scythia at the time.[1] By 370 AD, the Huns had arrived on the Volga, causing the westwards movement of Goths and Alans.[2] By 430, they had established a vast, but short-lived, empire on the Danubian frontier of the Roman empire in Europe. Either under Hunnic hegemony, or fleeing from it, several central and eastern European peoples established kingdoms in the region, including not only Goths and Alans, but also Vandals, Gepids, Heruli, Suebians and Rugians.

https://en.wikipedia.org/wiki/Huns

Mine layer I think means laying explosive mines? I dunno.