the mount pleasent vs the harrows

[Lukinsons]

hey, if i choosed go to the south, is it still possible go north later and do the side quest and etc.?

[Cairn.L]

Yes, you can.
Whatever your choice, the main story will take you there later on.

[Hotless]

yeah, you must do both of them before moving to the endgame and finish the game.

[M19*Haunter]

In case you wonder, the winter location should be the last, if we're talking about mobs difficulty.