The aristocratic Ummereise family originally came from Mecklenburg in Germany. They arrived in Sweden with Albrekt of Mecklenburg. Johan Ummereise the Elder may have been in the army which invaded Sweden in 1363. This army from Mecklenburg - together with members of the Swedish gentry - rapidly gained power in Sweden and Albrekt of Mecklen-burg was crowned King. As a gift of gratitude, Johan was given a splendid manor near Kalmar. He settled at Björnö and gradually he became the owner of a great many farms in Möre with peasants paying taxes to him. Johan was knighted Sir Johan. He might have participated in the battle at Falköping where King Albert’s troops confronted those of Queen Margareta. Many soldiers were killed in this battle, amongst others Vicke van Vitzen the Elder and very likely Johan Ummereise the Elder as well.
In 1390 the son Erik Ummereise took possession of Björnö. He acquired several farms in Möre and may well have been the richest man of the region by the end of the 14th and beginning of the 15th centuries. Erik joined Queen Margareta ´s side, and was knighted in Kalmar in the summer of 1397. Erik was a very influential man and many peasants were dependant on him. He owned a great deal of land and property in the parishes of Arby, Hagby, Halltorp, Hossmo, Voxtorp, Kläckeberga, Ryssby, Åby, Ljungby, Söderåkra and Torsås. In the parish of Vissefjärda he owned ten or so farms.
Erik also owned property on Öland. His farms lay in the parishes of Högsrum, Algutsrum, Gärdslösa, Glömmimge, Torslunda and Norra Möckleby. He also owned land at the crossing at Färjestaden.
After Erik had died his son, Johan Ummereise the younger inherited Björnö. He kept the manor until his death in 1440.
Many tenant farmers in Möre and on Öland came in close contact with the Ummereise family during the late 14th and early 15th century.