Aggra’s Pasture is an area of the Archylte Steppe that you can reach after you have completed Mission 14 - Defender of the Flock. Approach one of the Chocobos that appears in the Archylte Steppe after the Mission has been completed and use it to ride to the Eastern Tors area using the map below:
Approach the cliff and your Chocobo will automatically jump to the top ledge:
At the top of the ledge you will find a Treasure Sphere that contains seven 
Diabolic Tails. Travel through Aggra’s Trough passage way until you reach an open area with a 
Save Station which is Aggra’s Pasture. There is another Treasure Sphere in this area that contains six Gloomstalks.
You can complete the Sheep side quest:
You can also defeat the Ochu over in the corner that’s blocking a Treasure Sphere that contains a 
Platinum Bangle.
The battle against Ochu can be difficult even if you have been completing all of the optional side quests and Missions along the way through Chapter 11. The rewards from the Treasure Sphere are also not that great so if you’re having trouble don’t worry about coming back later when your party members are more powerful.
For the battle against Ochu, focus on Ochu rather than on the little Microchus. Defeating all the Microchus will cause Ochu to use an ability called “Seed Dispersal” which will summon five new Microchus for you to deal with. Use a 
Librascope at the start of the battle which will reveal both Ochu’s and the Microchu’s weaknesses.
Start off in a defensive paradigm, such as Evened Odds, and try to have your 
Saboteur get a range of debuffs active on Ochu (
Deprotect, 
Deshell, 
Imperil) to increase the damage done from regular attacks. Buffs are also very important, but they will be difficult to keep active as its “Screech” attack will remove them. Try to get them back up if you can anyway, but the more difficult aspect of “Screech” is just the sheer amount of damage that it deals (hence why having defensive status buffs can be important).
That’s all that you can do in this area. Use the link below to travel back to the optional side quest section of Chapter 11 if you are at that point of the game’s story:
