Quotation from: The Chessmen of Mars

Written by: Edgar Rice Burroughs

The game is played with twenty black pieces by one player and
twenty orange by his opponent, and is presumed to have originally
represented a battle between the Black race of the south and the
Yellow race of the north. On Mars the board is usually arranged
so that the Black pieces are played from the south and the Orange
from the north.

The game is won when any piece is placed on same square with
opponent's Princess, or a Chief takes a Chief.