The "Nihon Shoki", finished in 720 AD, is often said to be the first mention of Hokkaido in recorded history. According to the text, Abe no Hirafu led a large navy and army to northern areas from 658 to 660 and came into contact with the Mishihase and Emishi. One of the places Hirafu went to was called , which is often believed to be present-day Hokkaido. However, many theories exist concerning the details of this event, including the location of Watarishima and the common belief that the Emishi in Watarishima were the ancestors of the present-day Ainu people.