The story of Chess, according to Iranian mythological sources (recounted in Shahnameh) is that it was presented to the Iranian Court by the emissaries of the Indian Court, as a 'semantic puzzle' invented by Indian sages. (These games, it should be noted, were pedagogical in nature and used as symbolic means of training monarchs by the intellectual elites.)
The response of the Iranian sages was the invention of Backgammon, to highlight the role of Providence in human affairs.
The origin is unclear. The fact that the thematic of a game of war is prevailing now, to me means that it might have as well been in the beginning. Actually it shows at least that those semantics are relevant to war, and to live, so what I was saying stands.
Of course it involves war, but note how they teach the young prince it is (a) better to let the Vazier (your Queen) do all the heavy duty lifting, and (b) it is perfectly honorable to hide behind fortifications in a castle.
The response of the Iranian sages was the invention of Backgammon, to highlight the role of Providence in human affairs.
[p.s. not all Iranians are willing to cede Chess to the sister civilization of India: http://www.cais-soas.com/CAIS/Sport/chess.htm] ;)