As it is long and thin geographically and mountainous and in addition, close to Chugoku and Kyushu, it was exposed always to interference by the Mori clan and Otomo clan, and could not have the power to unify the country and to invade into the other countries.
地理的に細長く山岳地帯が多い上に、中国・九州と近いために常に毛利氏・大友氏の干渉に晒されることになり、一国を統一し他国へ侵略するような勢力を持てずに終わった。