ツァーリ (Tsar) refers to a title used to designate certain Slavic monarchs, particularly in Russia. The term is derived from the Latin word "Caesar," reflecting the influence of the Roman Empire. Tsars ruled from the 16th century until the early 20th century, with notable figures such as ピョートル大帝 (Peter the Great) and ニコライ二世 (Nicholas II) shaping Russian history. The role of the Tsar was both political and religious, as they were seen as the supreme rulers of the state and defenders of the 正教会 (Orthodox Church). The Tsar's reign often involved significant reforms, territorial expansion, and conflicts, ultimately leading to the fall of the monarchy during the ロシア革命 (Russian Revolution) in 1917.