I assume that by "Promised Land" you mean the crater on the northern continent and I'll use this assumption to answer your question. In short, the answer to your question is that, the barrier around the crater will remove itself when it's good and ready. Basically what this means is, the barrier will be removed when you've gotten to the point in the game when it should be removed and there's no secret lever to push to remove it. The barrier will be removed as the game progresses. I don't want to give too much away to you, but fighting Diamond Weapon is just about the last thing you do before the barrier is destroyed. If you haven't fought Diamond Weapon yet then you still have further to go. If you really want to know where you are in the process of getting into the crater, then read through this short timeline:

1. Aeris dies
2. Icicle Inn
3. Gaea Cliffs
4. Whirlwind Maze
5. Mideel
6. Stop the North Corel train
7. Fort Condor
8. Mideel
9. Ultimate Weapon
10. Wake up Cloud
11. Junon
12. Rocket Town
13. City of the Ancients
14. Diamond Weapon
15. Barrier destroyed

Hopefully that list can give you a good idea of how far away you are from the point where the barrier is destroyed without giving away the plot of the game. The only thing that could spoil things is that whole "Aeris is dead" thing, but I think most people in the gaming community know that fact by now whether they've played Final Fantasy VII or not. Anyway, good luck.

-DragoonMaster

dragoon blablabla is right

you cant until the sister ray destroys weapon and it in disc 3

its like they said but did u know the tiny bronco can fly and that 2 get a gold chocoobo all u need is the desert rose from beating ruby weapon and u can bring aries back 2 life as well and does any one know of any more secret chacters other than yuffie and vincent?