Merseburg was one of the most important cities in central Germany during the early to high Middle Ages. It was first mentioned in a written document dating from c. 890 AD. Among German history adepts it is well known for the "Merseburg Incantations" or "Merseburg Charms" (Merseburger Zaubersprüche), a collection of medieval pre-Christian, pagan magic spells written in Old High German in the 9th or 10th century. In 968 Emperor Otto I founded the Merseburg bishopric. The city which was then near Germany's eastern border, remained an important religious centre until the 16th century, being home to a Benedictine abbey and a Romanesque cathedral. Merseburg was one of Emperor Henry II's favourite palaces. The diocese of Merseburg was rather small but contained important cities like Leipzig.
In the mid 16th-century Merseburg adopted Protestantism. The Benedictine monastery was disbanded and the bishopric's territory annexed by the secular Electorate of Saxony. From the mid-17th to 18th century, Merseburg was the residence of its own branch line of Dukes. Under Prussian rule after the Vienna Congress of 1815, it was the seat of a governorate, administrating the south of today's Saxony-Anhalt (including the much bigger Halle).
In the 20th century, Merseburg and more importantly its suburb Schkopau became production sites of the chemical industry. The Buna works in Schkopau, founded in 1936 to support the Nazi policy of autarky, i.e. independence from imports of raw materials, was the first facility to industrially synthesise rubber. During the division of Germany, Plaste und Elaste ("plastics and rubber") from Schkopau was an almost proverbial household name in East Germany. Much of the historical old town was torn down to be replaced by "socialist" architecture. After the reunification many workers lost their jobs in the now unprofitable factories and Merseburg lost about a third of its population since the 1980s (it had some 34,000 inhabitants in 2015). The Buna works are now a subsidiary of Dow Chemical.