Blizzard Entertainment decided to trim the Auction House from the Vale of Eternal Blossoms’ capital cities: Shrine of the Two Moons (Horde) and Shrine of the Seven Stars (Alliance).
This is a logical decision. With all the over 100 daily quests, scenarios, dungeons, and grinding to do throughout Pandaria — people will rarely have an excuse to return to Orgrimmar and Ironforge/Stormwind.
The main capitals have always felt alive with people coming and going. Keeping the Auction House in the Vale of Eternal Blossoms would have anchored level 85-90 players to stay in Pandaria 24/7.
It also helps server stability to have players move around to other locations.
As with Cataclysm, the portals in the Vale of Eternal Blossoms are theme-coded. You can see the flags of each city behind the portals to make it easy to pick your destination. It was difficult sometimes in Dalaran to figure out which portal belonged to x or y city unless you hovered your mouse cursor over each individual portal.
The Horde portals lead to Orgrimmar, Thunderbluff, Undercity, Silvermoon City, Dalaran and Shattrath.
The Alliance portals lead to Stormwind, Ironforge, Darnassus, Exodar, Dalaran and Shattrath.