Final answer:
Legend says Alexander I went to Siberia and became a monk after his death in 1825, but this is not historically substantiated.
Step-by-step explanation:
According to legend, after the death of Alexander I in 1825, which set off the Decembrist Uprising, there were rumors that he had not actually died but had gone to Siberia and become a monk. These rumors persisted because of the mystery surrounding his death and the longing of some people for a more enlightened ruler than his successor, Nicholas I. There is no historical evidence to support claims of abduction by space aliens or that he fled to Turkey. The most commonly accepted account is that he died of natural causes, and the monk story remains a piece of apocryphal legend.