When did the Borg fight Klingons, Cardasians, Romulans, etc.

Ok I know that Romulans could have been fighting the Borg as per the “destroyed bases” aslong the neurtral zone thing from TNG.

But in the Voyager episode Unity, Chocotay is linked with the Borg and sees the Borg fighting D-7’s, Birds of Prey, Romulans, and other races.

When did this happen. And furthermore… How did the Klingons and Romulans, and cardasians defeat the Borg? They must have done a good job. I don’t believe that either race is so inferior that the Bog just chose to leave them alone. Becaus they assimulate worthless little cultures like Icheb and some of the other delta quadrant races.

In-Universe explanation: The Klingon and Cardie ships could have been long-range research/exploration vessels, or they could have been fleets providing assistance during the events of BoBW and FC (though undocumented on-screen). Also, due to the fact that the Federation piqued the Borg’s interest (see Q’s influence making it seem that the Enterprise can go warp 1billion) that they concentrated on the Federation, though only sending one ship at a time due to how far away the Alpha/Beta quadrant factions were away from Borg space.

Out-of-Universe explanation: they re-used footage from DS9’s Klingon war arc, and other ‘stuff blowed up’ shots from various points in TNG/DS9/VOY