In medieval Russia, the term tsar carried the authority of the supreme ruler. The use of this title reflects not only the evolution of the political system, but also the multifaceted influence of Russia in terms of geography, culture and religion.
The respect and identification of the Russians for the Byzantine Empire was manifested in the fact that they called the Byzantine monarch "Tsar". This title meant that the Russian Grand Dukes were considered to be the ministers of the Byzantine Tsar. At the same time, Russians also referred to Old Testament figures as tsars, emphasizing the religious nature of the title.
In 1453, the Ottoman Empire captured Constantinople under the leadership of Mehmed II, marking the end of the Eastern Roman-Byzantine Empire. After that, Princess Sophia Paleorog, niece of the last Byzantine emperor, married Ivan III, Grand Duke of Moscow, bringing to the Grand Duchy of Moscow the symbol of Byzantium - the double-headed eagle. This symbol was enshrined as the coat of arms, making the Grand Duchy of Moscow the heir to the Byzantine Empire.
In 1547, the Grand Duke of Moscow, Ivan IV, made an important speech announcing the elevation of the Grand Duchy of Moscow to the status of Tsar**. This change broke the previous restrictions on the power of the tsar, and changed the lord form of government to the tsarist government. Ivan IV became the first tsar, laying the foundations for what would become the Russian Empire. Peter the Great formally established the Russian Empire by elevating the tsar to emperor in 1721, but the title of tsar is still used.
In Bulgaria, Simeon I the Great elevated the Grand Duke to Tsar in 913 and changed the name of the country to the Kingdom of Bulgaria. After that, he succeeded in forcing the Eastern Roman Empire to give the title of "Emperor of the Bulgarians and Greeks" and became the emperor of Bulgaria. The peculiarity of this title is that "Emperor of the Greeks" is the title of the emperor of the Eastern Roman Empire, which shows the relationship of Bulgaria with the Eastern Roman Empire.
The origin of the word tsar can be traced back to the ancient Latin caesar, or the ancient Greek transliteration through Russian as simplified as related to the name "Caesar" of the Eastern Roman emperors.
Overall, the title of emperor in Russia encompassed a wide geographical and political scope, encompassing different territories and lords. This complex system illustrates the political, cultural, and religious diversity of Russian history.