842 Byzantine Emperor Theophilus dies and is succeeded by his son Michael III, the Drunkard. 844 Louis II is crowned King of Italy by his father the Emperor Lothar. 846 Muslim forces attack Rome. 850 Astrolabe perfected by Arab astrologers. An Arab goatherd, Kaidi, notices that his goats become more active after chewing certain berries.
Church mode is invented, the first step in the development of major and minor scales.
Ergot, a hallucinogenic fungus that grows on grain, is baked into bread, causing mass hysteria. 860 Hiragana phonetic script becomes popular among the ladies of the Japanese court, leading to the development of the novel 861 Norsemen attack Cologne, Worms, Paris and Toulouse. Libera nos a furore Normanorum. Deliver us from the fury of the Norsemen. 863 St. Cyril invents the Cyrillic alphabet.