This is the flag of Santiago communallity, not of the Santiago Region! Carlos Figueroa, 30 October 2004
This is the flag of the city of Santiago and the commune flag, not of the Region. Osmar Valdebenito, 6 November 2004
The flag of my city, Santiago de Chile. Coat of arms received from Emperor Charles V (I of Spain). The flag actually is used by the commune of Santiago. David López Pelen, 10 July 2013
Do you think the tinctures of the coat of arms were the source of the first flag? The one of "La Patria Vieja?" Gustav Tracchia, 10 July 2013
Interesting question. There's no official explanation for the colours of the Patria Vieja flag. It was in use for less than two years, even with different versions: Blue-White-Yellow, White-Blue-Yellow, White-Blue-Yellow with Red Cross of Santiago... The most extended meanings for the colours are "Majesty, Law, Force," but just that.
There's a theory that Blue represents Chile (Blue sometimes is considered as colour of the Kingdoms of Indias->Spanish America), Yellow for Spain and White in the middle as an expression of friendship or peace between them. But it's just a theory. David López Pelen, 11 July 2013
Is not Patria Vieja a source. Colours are from Spanish crown suggest. Yellow for 8 lines (veneras or shells) of gold, and blue is just a sky background (campo). Lion with nude sword is an Spanish heritage symbol (Castilla y León, or Castile and León).
Arms of Santiago: 1552, February 12. Cristian Herrera, 14 June 2016