A generation ago the Lion Clan came into possession of a most curious gaijin artifact, one of those things called a "book." But this was not simply any book, but rather a copy of De Bellis Yoditorum: an ancient treatise on the many tactics and strategies employed by the Yodotai, a vast and ruthless culture of warriors that lies far north and west of Rokugan. After significant difficulty, the Lion scholars were able to translate the text into the Rokugani language, and examination of its contents began in earnest.
Although the Lion have considerable appreciation for the information in the book, its existence has only enhanced their disgust toward cultures other than their own. Nevertheless, they have carefully studied everything within, training special units of their soldiers to employ and to counter the gaijin tactics on the field of battle. Some among the Lion believe their understanding of the book has placed them in a unique position to defeat the Yodotai, should those conquerors ever trouble the Empire. However, scholars who are more familiar with the text are deeply troubled by references that imply it is but one of a larger series of works.