Medieval maps of Paris were oriented West-East, thus offering the best views of church facades!
Note that this is a personal opinion shared as a child with my grandfather after years of family diner in front of his Truschet map.
For sure, there is no connection with "rive-gauche" / "rive-droite", this expression is based on the flow of the Seine, here it would have been the opposite of the map.
Medieval West-East maps on wiki (West on the top, North to the left):
- 1530 Braun and Hogenberg engraved map [1]
- 1550 Truschet and Hoyau engraved map [2]
- 1615 Merian map [3]
- also the 1370 Gough Map of Britain [4]