title: Russian Empire
context: The Russian Empire,[lower-alpha 5] also known as Imperial Russia[lower-alpha 6] or simply Russia,[lower-alpha 7] was an empire that existed across Eurasia and North America from 1721, following the end of the Great Northern War, until the Republic was proclaimed by the Provisional Government that took power after the February Revolution of 1917.[4]
question: When was the Russian Empire started?
answers: 1721