A large inspiration for the Wardley Mapping method comes from Sun Tzu's The Art of War, and from John Boyd's OODA Loop. The five factors of competition described there were Purpose - Landscape - Climate - Doctrine - Leadership. 
It doesn't matter whether you're competing against a foe in a battlefield, or in a game of chess or in business ... strategy always starts with where. "Where can I move?" is the first question you must ask. To do this then situational awareness (i.e. understanding your environment) is critical. If you cannot visualise (even through mental models) the landscape then you cannot determine "where". Mapping is fundamental to strategy and to organisational learning (e.g. economic lessons and repeatable gameplay in business or battle plans in military history) because situational awareness is.
Landscape is the environment that you compete in. It describes the position of troops, the features of the landscape including any obstacles in your way.