I lost track in the first couple of sentences. «On March 30, 2023, Brazil and China signed a deal to enable mutual trade and investment directly through the loc

I lost track in the first couple of sentences. «On March 30, 2023, Brazil and China signed a deal to enable mutual trade and investment directly through the local currencies, casting aside the United States dollar as an intermediary.» Wasn't that possible until now? Why not? Does this mean that the yuan and the real weren't convertible without an interediate currency? Or was there some law in one of the two countries?