Below is a walkthrough for the Pocket Sandstorm side quest in Tiny Tina’s Wonderlands. To obtain this quest, speak with Blatherskite in the Overworlds.
Reach ruins
Travel to the objective to find the dungeon then head inside and complete the encounters. Loot the Bag of Containment from the chest.
Talk to Blatherskite
Speak with him to complete the quest.