User blog comment:Kogath/Monster Hunter 4 Ultimate for the Nintendo 3DS/@comment-6050823-20141029004407/@comment-17735225-20141029043721

The town's weapon upgrade and George's story sort of gives it out that 4th gen takes place after 2nd gen in the first place.

3rd doesn't really have much connection to prior gen (I think?). 4th gen actually explain Zinogre's original habitat but it can't be use to conclude when 3rd gen actually happen.

1st and 2nd gen's timeline is really confusing. At the end of MHdos offline, after we banish Lunastra from the tower Jumbo village's chief set out and manage to 'rediscover' Kokoto village,returning after we actually slain Lunastra(which can be within a day due to game mechanic = = ). Then we are allowed to go to Kokoto and we discovered that there's Hero of Kokoto already (the protagonist from the first game). So I guess 2nd gen took place long after the 1st gen (enough for Kokoto village to dissipate).