@ the great wall...
The gunpowder is to the bottom right side. If it isn't there, you may have already picked it up (look in your item bag). If you still can't find it, go to the Viking site (831 AD) and see what happens when you get in front of the rock cave. As a last resort, leave Time Tangled Island, re-boot Poptropica, and then come back. It may be a transient glitch in the program.
No TNT, but some gunpowder that will work. Go to the Great Wall of China (1593 AD) and get the barrel of gunpowder at the far right. You can use to to blast open the cave at 831 AD to recover the Golden Vase.
You need to find the gunpowder (in the 6th place from the lab going clockwise). Then go to the 2nd place from the lab clockwisley and go up to blast the cave.
you dont
inside a temple
you find your self in the future(seconed time)
The pumpkin head is in Time Tangled Island and you have to find it.
The cave is located in 0831 AD.
I don't think there is one.
In the Aztec period, you get them from the warrior.
on time tangled island [vikings]
Go to China ( place with the big gray wall being built ) and run to the right until you see a the gunpowder barrel on a platform .