Do you have any evidence to back your statements? They appear to me to be personal beliefs which are at odds with my understanding of the development of cartography. So far all you've done is repeat yourself.

My hypothesis is that different northern hemisphere civilizations used different conventions to orient the map. For example, the primary convention for Middle Ages Europe was that east is at the top of the map. This is well attested. See not only the links I gave but the following links:

http://www.turkeyinmaps.com/Medieval.html shows 8 medieval maps. 1) The
T-O map of Isidore, "east is towards the top of the map, 2) Beatus World Map, "The east is to the top of the map", 3) World Map of A-Idrisi, "the south is oriented to the top of the map", 4) Ebstorf Mappamundi
where the map is "superimposed on a background of the figure of Christ crucified; with His head at the top (East), His feet at the bottom (West) and His hands pointing North and South, an orientation that dominated medieval European cartography" (click on the map for that description; emphasis mine), 5) Hereford Mappamundi, "As previously mentioned, East is at the top of the map", 6) Vesconte Mappamundi, "circular in format and oriented with East to the top", 7) Higden World Map, "oriented with East at the top", and 8) The Catalan Atlas (likely north; the link says it was a portolan chart, 'intended to lie on the chart-table of a ship and always was oriented to the necessities of navigation, thus there is no 'orientation of priority' of such maps. ... however, as the legends that are legible prevail in north-orientation, in the modern literature of the maps the north-orientation is now adopted.)

So that one page shows 6 east-as-top maps, 1 south-as-top, and 1 north-as-top.

Another link is http://www.medievalists.net/2013/07/28/ten-beautiful-medieva... : 1) Madaba Mosaic Map, which Wikipedia says is 'not oriented northwards, like modern maps, but faces east towards the altar in such a fashion that the position of places on the map coincides with the actual compass directions.' 2) The T-O Map of Isidore of Seville (east, as already mentioned), 3) Saint Beatus of Liébana (east, as already mentioned), 4) Tabula Rogeriana (which I previously commented was an Arab map with south at the top), 5) Matthew Paris’ map of Great Britain (a regional map, with north at the top), 6) Hereford Mappa Mundi (already mentioned, with east at the top), 7) The Vinland Map (perhaps a forgery; north at the top), 8) The Maps of Piri Reis (another portolan chart with no preferred direction), 9) Carta Marina (north), and 10) The Gallery of Maps in the Vatican, where the image given shows Sicily oriente with south at the top.

That's 3 north-at-top maps out of 10.

So, am I really cherry picking or are you simply incorrect about your understanding of cartographic history?

I invite you to show me a list of other medieval European maps where a majority have north at the top.

P.S. Your statement that I 'simply grabbed a list called "Early world maps" off of wikipedia' is provably incorrect. I also listed two maps (the early Western Han Dynasty map and the Psalter map) which are not on the "Early World Maps" page.

Feel free to count for yourself the number of pre-Mercator maps on the 'Early world maps' which use a direction other than north for the top of the map. Your hypothesis is that few if any should have anything other than north at the top, but that's easily seen to be incorrect. Observational evidence so far is more in line with my hypothesis.

P.P.S. You said " The Nile Begins its flow South of the Equator and flows towards it before emptying in the nearest large body of water, the Mediterranean." However, 1) water doesn't flow to the nearest large body of water but rather it flows downhill, and 2) while the headwaters of the Nile is at 2 degree south latitude, the largest nearby body of water after crossing the equator is the Indian Ocean, approximately 1000km away instead of 5000km.

And did the Greeks know where the Nile began? Wikipedia at https://en.wikipedia.org/wiki/Nile#Search_for_the_source_of_... says that "no European of antiquity is known to have reached Lake Tana", which is in Kenya, in the northern hemisphere. Why do you think the Greeks thought that Nile started from below the equator?