Quoting from the family history which was last updated in Germany in 1938, the old genealogies suggest the name could be older than 1234. It appears the origins are west of the Elbe river. The written family tree goes back to the year 1333, but there are earlier mentions including Aluericus(Alverish) de Blanckensee in a Latin document in a monastery in Lehnin, and 1253 Wasmusdus de Blanckensee as a witness in a Hessian(German Duchy) document.
Family estates of Blanckensee have included the Zipkow estate which was in the family from the 1790’s until 1945. It is now a pig farm and located about 80kms east of present day Slupsk near the Baltic in Poland. Other family estates were in Prussia between Slupsk and present day Gdansk.
An estate called Schlagenthin was in the family from the early 1300’s to 1796. Once owned by Gyso Von Blanckensee, first mentioned in 1333 and a witness in a document in 1370.