Some information about Vaniae
by WingofCootA couple of other thoughts on Vaniae, not directly related to the sandfolk or Tharsis...
Size: For simplicity, Vaniae's circumference is 12,960 miles (diameter ~ 4125 miles). This is very close to Mars' actual size, and it works out neatly in hexes: 12,960 / 360 = one degree of latitude is 36 miles, so one 72-mile hex north to south represents 2 degrees of latitude.
Time: The Vanian year of 668 (local) days is divided by most local civilizations into five 133-day "seasons" and five festival days. This calendar is very old, and Vaniae's climate has worsened significantly since it was invented; even then, the "seasons" correlated with the actual climate only in the south temperate zone region where it originated. Now, they are valued only for ceremonial and record-keeping purposes.
The five seasons correspond to the five Spheres and represent Water (originally beginning with the first snow-melt and corresponding to spring), Fire (summer), Earth (early fall), Air (late fall/early winter - the season when storms are most likely to occur), and Death (midwinter / late winter).