Most Lore and Legend Quests can be started either with a book or by examining one of the quest items. Find the book, A History of the Centaur (Book) (Version 1), using the location information above. Next, read the book, A History of the Centaur (Book) (Version 1), flip through all the pages, and accept the quest. Once you have accepted the quest you may place the book in your house. You do not need the book to progress the quest.
Steps
Find the following auto-updating pieces by killing Centaurs in any zone:
a centaur spirit
a centaur heart
a centaur brain
Find and examine the following tradeable pieces obtained by looting Centaurs in any zone, or buying them from other players