I did Marks 1-2. Mark 3 directs you back to where you came from (SPOILER)(Where Hope beat Alexander). Just keep going and you'll reach this area called Yasch something (I can't spell it for the life of me). Anyhow, the monsters there are much more friendly than the ones in the open space and there are more Marks that you can do. Granted, the monsters are still difficult and there are some King Behemoths, but eventually I was able to level up my characters to a decent level where not even the King Behemoths are a problem to me anymore. )

Good luck and hope this was helpful.