Ismailov Shohrukhmirzo, a doctoral student at the Khorezm Mamun Academy, found a coin in the collection of coins of the University of Tübingen, Germany, which was minted in 967 AD in Georgia (Old Urgench). This coin was minted by the Samanids by Muhammad ibn Ali, who was appointed viceroy of Georgia. The inscriptions on the coin are very similar to the coins minted by the Mamunid dynasty, and the name of this coin, Muhammad ibn Ali, is believed to be the father of Mamun ibn Muhammad, who is now considered the founder of the Mamunid dynasty. This idea is supported in the research of Uzbek researcher A. Atahojayev. This news raises some questions in the history of Khorezm in the 10th century, including the secession of the city of Jurjaniya (Old Urgench) from the African Khorezm state, the establishment of an independent emirate there, the rise of the Mamun dynasty and the Mamun dynasty. clarifies the issue of the founder. Today, research on this issue is being carried out in collaboration with A. Uzbayraktar, a researcher at Amasya University in Turkey.