The Kingdom of Bulgaria was a historical state in Southeast Europe, established in the late 7th century. It played a significant role in the region's development, particularly during the Middle Ages. The kingdom reached its peak under the rule of Tsar Simeon I, who expanded its territory and promoted the spread of Slavic culture and the Cyrillic alphabet. The kingdom experienced various periods of prosperity and decline, facing invasions from the Ottoman Empire in the late 14th century. Ultimately, Bulgaria fell under Ottoman rule for nearly five centuries, which significantly influenced its culture and society. The Kingdom of Bulgaria was officially restored in 1908, becoming a modern nation-state.