In "Dalek" (2005), the Ninth Doctor explains that his people perished along with the Dalek race in the "Last Great Time War", leaving the Doctor the last of his race. In "The Satan Pit" (2006), the Beast identifies the Tenth Doctor as "[t]he killer of his own kind." In "The Sound of Drums" (2007), the Master reveals he escaped the war by turning himself into a human following the Dalek Emperor taking control of the Cruciform. In "The End of Time" (2009–10), the Time Lords, after attempting to break out the time lock of the Time War and become creatures of consciousness, are shown being sent back into the War on the last day through the Tenth Doctor's intervention. The Master also disappears along with them. Rassilon describes Time Lord history in this story as having lasted "a billion years" up until the end of the Time War.