It was a time of lawlessness and anarchy following the death of Fyodor I, a weak and possibly intellectually disabled ruler who died without an heir. His death ended the Rurik dynasty, leading to a violent succession crisis with numerous usurpers and false Dmitrys (imposters) claiming the title of tsar. Russia experienced the famine of 1601–03, which killed almost a third of the population, within three years of Fyodor's death. Russia was occupied by the Polish–Lithuanian Commonwealth during the Polish–Russian War (also known as the "Dimitriads") until it was expelled in 1612.