Well, you got the "south" part right.
Its a flag for what I imagine a reformed Gran Colombian Confederation would be.
Consisting of Venezuela, Ecuador, Peru, Colombia, and Bolivia, it draws on inspiration from all five republics. The red is universal amongst all five, so I used it in the vertical third. All save for Peru use yellow, which takes the top top horizontal third. The original three republics use differing shades of blue, so to make it stand out a bit, I used Venezuela's for the central third. And as Bolivia is the only nation that uses green, it occupies the bottom third; which is also fitting as it serves as the bulwark against the southern nations of Chile and Argentina.
I'm curious if I should make additions however. Maybe the simple addition of five stars for each constituent republic?