Please upload if you have or say how can I extract them from wherever they are in the game :confused:

In the Assets subfolder in your vanilla civ4's install directory you will find fpk files. You need to unpack them via a certain program whichs name I forgot, but which you'll find in the tools section of civfanatics download area. So, unpack those fpk and you shuld get an Art/Interface/TeamColor folder, besides some other. There are the flags!