There are currently six sub-series, each containing six books. The first, Warriors (later re-titled as Warriors: The Prophecies Begin), was published from 2003 to 2004. Warriors: The New Prophecy, published from 2005 to 2006, follows the first sub-series, chronicling the Clans as they move to a new home. The third story arc, Warriors: Power of Three, was published from 2007 to 2009. The fourth sub-series, Warriors: Omen of the Stars, was published from 2009 to 2012 and continued where the third story arc left off. The fifth sub-series Warriors: Dawn of the Clans, was published from 2013 to 2015. The sub-series acts as a prequel series, detailing the formation of the Clans. The sixth and most recent sub-series, Warriors: A Vision of Shadows, is still on its fourth book and halfway finished. The first book of the sixth series, The Apprentice's Quest, was released on March 15, 2016, and the second book, Thunder and Shadow, was released on September 6, 2016. Warriors: A Vision of Shadows follows Warriors: Omen of the Stars, and Bramblestar's Storm.