The north-south position, like many positions in Brazilian Jiu-Jitsu, is common in Judo and martial arts. Your opponent is held with their back to the ground while you lay over their head and chest with your legs pointing opposite of theirs. This position on the top is extremely useful to attack Brazilian Jiu-Jitsu players who extensively use their legs and guards due to position your body and legs as far away as possible from their legs. This position is extremely frustrating to defend on the bottom, for the very same reason, because it leaves your head and arms extremely vulnerable, with your legs too far away to easily defend or counter by attacking the opponent.