Bundahishn 11

On the nature of the earth it says in revelation, that there are thirty and three kinds of land.

On the day when Tistar produced the rain, when its seas arose therefrom, the whole place, half taken up by water, was converted into seven portions; this portion, as much as one-half, is the middle, and six portions are around; those six portions are together as much as Khvaniras.

The name kêshvar (zone or region') is also applied to them, and they existed side by side (kash kash); as on the east side of this portion (Khvantras) is the Savah region, on the west is the Arzah region; the two portions on the south side are the Fradadafsh and Vidadafsh regions, the two portions on the north side are the Vôrûbarst and Vôrugarst regions, and that in the middle is Khvantras.

And Khvaniras has the sea, for one part of the wide-formed ocean wound about around it; and from Vôrûbarst and Vôrugarst a lofty mountain grew up; so that it is not possible for any one to go from region to region.

And of these seven regions every benefit was created most in Khvaniras, and the evil spirit also produced most for Khvaniras, on account of the superiority (sarih) which he saw in it.

For the Kayânians and heroes were created in Khvaniras; and the good religion of the Mazdayasnians was created in Khvaniras, and afterwards conveyed to the other regions; Sôshyans is born in Khvaniras, who makes the evil spirit impotent, and causes the resurrection and future existence.