BPD is the standard measurement of time in Amsnorth. It is used to tell the age of characters, places and more. However before this actually was invented, many of the people of Amsnorth did not use time to understand the use of age.
BPD stands for Before Purple-eye's disapearance.
History[]
The time code was invented when Purple-eye, a dragon was taken from Seatown. This spurred many events that led up to the future novels.