The Qur'an does not appear give any particular significance to this latitude line.
Perhaps many things happened at/around this latitude line because the climate at this latitude facilitated agriculture, transportation (especially via the Mediterranean), and hence the growth of empires.
Of course, there are many peoples and civilizations that arose at other latitudes. For geographical reasons, the early Muslims would have been less familiar with more faraway civilizations. As for prophets, God says that prophets were sent to all peoples.
From a Qur'anic perspective, the most significant place is the site of the Ka'bah in Mecca, and that is not on the 33-degree latitude line.
God knows best.