>>531638218
They find it during the ending of DK '94, according to Miyamoto in an interview about the game:
>Is Pauline Mario's girlfriend?

>Kameyama: She's his ex (laughs).

>Miyamoto: The Mushroom Kingdom looks to be on the outskirts of Donkey Kong's homeland, as seen in the game's ending… I guess Mario met Peach there and his eye started to wander (laughs).

>Kameyama: In other words, this takes place before Super Mario Bros. Later on, after Mario became famous, he probably gave Pauline the flick (laughs).