Member of a warlike nomadic people of Central Asia and Eastern Europe whose leaders included Attila and Bleda (3)
I believe the answer is:
hun
(Other definitions for hun that I've seen before include "One of Attila's people" , "Warlike nomad" , "Attila the ... invaded Europe in 5th century" , "Attila was a notorious one" , "One of fourth to fifth century invaders of Europe" .)