You know, even if the Haches didn't participate in the Drac War they could have picked up some salvage from Drac ships. A scrap of metal from one of there ships alone would benefit the Haches greatly, and I would see them as getting the remnants of ships reasonable.

Also if the Equestrians are allied with the Hach its likely they already established trade routes.
Also conquering the Haches was more of a joke.