the romans - intelligently - realized that there were endless streams of perpetual barbarian hordes. you could fight one horde to the death, only to get ambushed by the next one. trying to actually defeat the barbarians was a sisyphean task of endless futility that made existence mundane. you can't be an artist, or a philosopher, if you have to waste your whole life fighting barbarians.

instead, they'd get the barbarians to fight each other. they'd trick them, constantly. they'd get one group to make deals against the other, they'd spread false rumours (did you know that gog, leader of the gazundhites, is gay? or that his family dresses like peasants?....who say this about gog? grrrrrar. the gazundhites will blow you out of existence.....), they'd arm both sides, or pay one group to protect them, and the other to fight. they set up a kind of conveyor belt so that the closest barbarian was always fighting the next furthest one, but then they'd always make sure the closest one would lose by turning on the closest one, and then getting the one that replaces it as the new closest onr to fight the next furthest one. this was referred to as imperial treachery, and it was like something out of a long running saturday morning cartoon. i'll get you next time, basileus!

so, the history is full of these tactics utilized to get the barbarians to fight each other instead, and it was always just to get them to war outside of the empire instead of in it.

hey, it worked for a thousand years. in the end, it was really the french that destroyed them, not the turks, and the romans made the mistake of letting the french in the city. their tactics didn't fail them. they got stabbed in the back.