It comes as little surprise that the atlas begins in the west and works (for the most part) eastward. It is the vertical stacking of the sheets, visualized in color, that strikes me as noteworthy. The north-south orientation makes good sense in the context of a bound atlas, where proceeding through geographical space in consistent, logical order would allow a reader to navigate mentally.
But in more abstract terms it represents a refreshing deviation from the horizontal axis structuring so much of what we think about the nature and identity of the empire. The series of lines descending into the southern reaches of Eurasia recall both the geographical perspective of the tsars looking out from their northern palace and the ancient Greek understanding of a world divided between north and south, darkness and light, snow and sun.