As you're leveling up, there is going to be plenty to explore and plenty to do. One of the things you're going to notice sooner or later is that there are a bunch of new factions to earn reputation points with. This expansion does two things really when when it comes to reps. First is that reputation isn't quite as hard or tedious as it has been in previous expansions, which is most welcome. Second is that the rewards that each faction has to offer you can be quite awesome for your chosen Warcraft profession.
The Shado-Pan clan are a very interesting faction as far as the pandaren are concerned. They are much more dark and sinister when compared to the other factions. They resemble more of closely to the ninjas of the old stories than the kung-fu masters. They are considered the most elite warriors of the pandaren dedicated to fighting against the Sha. Players will first encounter them in full at the Shado-pan Monastery, one of the new 5-man dungeons in Mists. Leveling your rep with them nets you some very nice rewards that you can buy with Justice Points and Valor Points.