The first flag of the Iberian UnionA great, clear flag, or so many people think. Note though, that the Iberian Union employs a different flag since they made peace and annexed the Hispanion Union, which is considered the transfer from semi-civilized to fully civilized by many. This flag also represents the semi-civilized people (at that time) of the Iberian Union. To the right, we have the original banner of the Iberian Union. Much red, which indicates blood and war, with a small yellow stripe which indicates that the Iberian Union is good, great, the light in the darkness, the beacon of hope, that kind of things. And the spikes refer to their barbaric past. In the middle is the official color of the Iberian Union, a light shade of blue, possibly representing the sky, for the barbaric Iberians (before forming their semi-civilizations) were a highly religious and mystic people, having many knowledge of stars and plants, and such things. To the left is the orange of Carthago, probably because their semi-civilization was based on Carthago, heavily influenced by it, and originated on their borders.
The current flag of the Iberian Union
The current flag is simply red with yellow, based on their original banner from the time that they were barbarians. It is perhaps strange that they don't use their shade of blue any more, but it is entirely logical that they have discarded the use of the orange of Carthago, they were independent now, and they had annexed another nation. Probably, the Hispanion Union also influenced the Iberian Union on deciding its new flag. It still remains largely a mystery why exactly this flag has been chosen for the new (and current) flag of the Iberian Union.