I've played through FFX at least 5 times and not once have I heard in the game how Jecht ended up in Spira. I heard from other people that dream Zanarkand is an actual location in Spira and that it is protected by something so that no one can get in except Sin and that Jecht just traveled out to sea to far one day and bumped into Sin and thats how he got through. Can anyone stand behind this or know anything? Maybe I'm missing something in the story..