As the book says, 'The barbarians are unaware of the unit of ri and they count the distance by days; its national boarders are five month from east to west and three months from south to north by a ship, surrounded by the sea; also the east is higher and west is lower in altitudes; the capital of Yamatai Kingdom is in Yamadai Kingdom according to Gishi-wajin-den (the first written record of Japan's commerce),' Wa people did not know about the unit ri (one ri is approximately 3.927 kilometers) used for distance measurement and instead they used the number of days they needed to move from one place to another.
「夷人不知里數但計以日其國境東西五月行南北三月行各至於海其地勢東高西下都於邪靡堆則魏志所謂邪馬臺者也」とあり、里数を知らず日で距離を測る。