Originally Posted by tengri khan
While hundreds of thousands of xiongnus have been defeated and conquered by han dynasty？
Some people say huns are not xiongnu，but I think they are similar people，just like the relationship between turks and mongols.
Truth be told, they conquered the then weaker, less inhabited half of Europe, so that helped.
They were a very uncivilized bunch in that they lacked settled communities and central leadership. Moreover they were highly mobile and trained from a young age in horseriding and the use of their composite bows. The composite bow was new to Europe, and where the Huns rode there was none to match it. This made it possible for them to strike anywhere and made them virtually impossible to retalliate to to their foes.
Like most Steppe peoples the Huns tended to incorporate defeated tribes in their armies. If the host was big enough Steppe invasions would dry up in its human reservoir. At first the Hun ran into the germanic peoples who then lived from the the northern Black Sea shores to the banks of the Rhine. By the time of Atilla an Idunno-how-many-but a large part of his army was germanic. Hun warlords would gain followers and status if they could win on the battlefield and consequently provide booty. I suppose that is the best you can expect from any warlord... This concept surely wasn't alien to the germanic world.
And, yes, soon enough the Hun warlords, with their germanic allies, would find a formidable prey to suck booty from: the Roman Empire, the other, wealthier, militarily stronger and more populous part of Europe. At first often Huns would fight alongside the Romans, to crush the occasional pesky germanic tribe here and there... But as the gold beckoned, you could say the Huns centralised in their efforts to suck the gold out of the Roman empire. That empire was a tad out of balance at that time, being divided into two halves that failed to coordinate efforts against invaders.
So, in the end, i'd say the Huns dominated, rather than conquered, half of Europe (and for a brief moment more than one half) thanks to their lifestyle which gave them a military advantage initially and their system of leeching applied to a formidable prey like the Roman empire. The Huns were formidable, because the Romans were formidable. Jmo.