Mongseng
Mongseng is a plane that is depicted by the card Kharasha Foothills. The card shows warriors on a battlefield with flags on their backs, bearing resemblance to the sashimono-carrying samurai, but also possibly used in traditional Chinese warrior culture.
Mark Rosewater has stated that the planes showcased in Planechase (2009) and Planechase (2012) were created as potential locations for future stories.[1] When Khans of Tarkir was revealed at San Diego Comic-Con 2014, Kharasha Foothills was mentioned as the source of inspiration for the plane of Tarkir. However, Mongseng was rebranded to Tarkir, just as Arkhos had been rebranded to Theros.[2] Mark Rosewater has stated that bigger factors than continuity led to the name change, which prompted a commenter to observe[3] that the earlier name could be read as containing a slur.