There are two parts of the quest chain for each continent. The first part involves defeating numerous Master Pet Tamers, and the second requires you to triumph over the Grand Master Tamer. After you've bested the Grand Master Tamer, dailies from each Tamer will unlock for that continent. All the dailies continue to reward experience for your companions, however only the Grand Master daily quest will reward the Sack of Pet Supplies.
Oct 24 A Return to World of Warcraft: Player Guide So you’ve decided to return to World of Warcraft. Welcome back! There’s just one thing you’ll need before jumping back into the fray—knowledge. To aid you in making your glorious comeback, we’ve compiled some handy information every returning hero should know. Once armed with knowledge, nothing (and no one) will stand in your way. http://us.battle.net/wow/en/blog/8876440/Nethaera214 Oct 24
2. Achieving. There are many pet battling achievements in game, and following the natural trail through the Taming [Continent] achievements up to Pandaria, and then on to the Spirit Tamers, Beasts of Fable and the Celestial Tournament was an epic journey for me and for many others. It's well worth doing. The Celestial Tournament is still, IMO, the pinnacle of PvE pet battling. However, WoD and Legion and BfA have added more battling achievements.