Shang explains that he intends for you, Ji, and Aysa to leave and bring what you have to give out into the world so that you might give it.  The ideals of both sides of the great conflict, he says, have differing ideals- but both have only the best of final intentions.  The choice, therefore, is up to you- speak to him again when you are ready to leave, be it with Alliance or with Horde.

When you accept this quest, A New Fate, Master Shang offers a discussion.

He confirms his pride in the three of you, and mentions that the outer world is broken and needs help.  Aysa tells him that she wishes to accompany the soldiers of the Alliance to their home.  Shang turns to Ji, and asks him if he wishes to go with the Horde.  Ji confirms this, saying it may be for the best- as he likes what he knows of them and they seem to need help.  That set, Shang then asks you what your decision is.

At last, you are granted the opportunity to choose to join the Alliance or the Horde, accompanied by a special set of banners and a brief explanation of each.

The views provided on the scroll you see are, interstingly, a bit tilted- only virtues are mentioned of the Alliance, while one of the foibles of the Horde , its inherent aggressiveness towards anything that conflicts with the overall viewpoints of the group, is given some mention.  It’s worth noting that this is a thoroughly permanent decision as well, and if you didn’t have a selection in mind before you created your character, it’s a good idea to take into consideration both sides.

In terms of the game lore, the Alliance and the Horde have somewhat different mentalities- where the alliance tends to be focused on the concepts of virtues and following some rather lofty ideals, the Horde tends to be more grounded in realism with a focus on acting not necessarily practically, but directly regardless of the situation.  The Alliance’s main theology relates to the Light and righteousness, where the primary Horde thinking is inclined along the lines of nature-worship and the rights of its races to hold their own places wherever they may be found.  While the Alliance can be arrogant in its application of its ideals, the Horde can be brutish in the implementation of its own goals.

There is also the playerbase to take into account, a distinctly out of character element.  While the Horde players tend to be more competent and competitive in the PvP areas, there’s a certain amount of elitism that has taken root in that.  This is not to say that all Horde players or even an overwhelming majority are arrogant over their side’s victories and heavily focused on player-versus-player content, but there is a rather vocal portion of the playerbase that falls into that category, and the overall tendency is in that direction.  By the same rote, those who play mostly on the Alliance side tend to be more along the lines of casual players who play the game as a game rather than a competitive sport.  This is not to say that no or too few Alliance players have competetive spirit, nor that you are going to have too much trouble finding an Alliance player who puts real effort into their game or equipment selection, only that the players tend to be a bit more relaxed overall.

Whichever your decision, make it carefully- you’re almost done with the entire introductory story arc.