This theory is persistent, based upon the following facts; the army of the Mongol Empire in many cases performed several reconnaissances in a phased manner before a serious invasion, with a number of soldiers varying from a hundred to ten thousand; arrows run short soon in the Yuan army as described in 'Nihon Den' of "Genshi;" and the number of soldiers was small, about thirty thousand (including non-soldiers).
根拠として、本来モンゴル帝国の軍事行動では、事前に兵力100〜1万規模での敵地への威力偵察を数度段階的に行った後、本格的な侵攻を行う場合が多く、また『元史』「日本伝」には元軍の矢がすぐに尽きたという記述が見られることと、3万人程度（中には非戦闘員もいる）という少ない兵力からこの説も根強い。