sciomancy n.

inhabitants of the torrid zone, 1630s, from Medieval Latin Ascii, from Greek askioi, from a- "not, without" (see a- (3)) + skia "shade, shadow," which Beekes derives from PIE *skhieh- "shadow" (source also of Sanskrit chaya "shadow," also "image;" Persian saya "shadow," Albanian hie "shadow"). So called because they "haue the Sunne twice euery yeere in their zenith, and then they make no shaddowes at all" [Nathanael Carpenter, "Geographie Delineated forth in Two Bookes," 1635].

word-forming element of Greek origin meaning "divination by means of," from Old French -mancie, from Late Latin -mantia, from Greek manteia "oracle, divination," from mantis "one who divines, a seer, prophet; one touched by divine madness," from mainesthai "be inspired," which is related to menos "passion, spirit" (from PIE *mnyo-, suffixed form of root *men- (1) "to think," with derivatives referring to qualities and states of mind or thought). Compare mania.