"The black Heunisch is said to have been brought to the Saale as early as the 8th century. It belongs to the complex of varieties of medieval sloe grapes, whose ancient home is on the south side of the Carpathian arch. The Black Heunisch is a typical relic from the early and high Middle Ages, when the tree line in Europe was 100 m higher and the continental summers were the rule as in 2003 and 2018. (https://historische-rebsorten.de/rebsorte/schwarzer-heunisch/)