Natt och Dag (, literally "night and day") is a Swedish noble family and the oldest surviving family of pure Swedish extraction, with origins stretching back at least as far as the late thirteenth century. However, the actual name Natt och Dag, alluding to the contrasting colours of its coat of arms, was not coined until the sixteenth century, and was not used as a surname by the family itself until the eighteenth century It is therefore customary to write the name in parentheses (e.g. Bengt Stensson (Natt och Dag)) when applying it to individuals prior to 1700. History The family's oldest known ancestor is the knight, Lawspeaker of Värend, and Councillor of the Realm Nils Sigridsson (Natt och Dag), who is first attested in a document from 11 May 1280 and lived at Ringshult, near Torpa in Östergötland. It is possible the family's origins stretch even further back. Gabriel Anrep, a Swedish genealogist of the 19th century, wrote: In the fifteenth century, the family split into two branches. The junior branch, descended from Bo Stensson (Natt och Dag), adopted the surname Sture, although they continued to bear the Natt och Dag coat of arms, and thus are sometimes considered either as an offshoot of the Natt och Dag or as a separate dynasty, the Younger Sture Family. The Younger Stures enjoyed great prominence in the late fifteenth and sixteenth centuries. Svante Nilsson and his son Sten Sture the Younger ruled Sweden as regents () during the period 1503-20, and Sten's sons Nils Stensson Sture and Svante Stensson Sture, and the latter's son Nils Svantesson Sture, were all important figures in Swedish politics during the reigns of Kings Gustav I and Erik XIV. This branch became extinct with the death of Svante Mauritzson Sture in 1616. The senior branch of the family was descended from Bo Stensson's elder brother, Bengt Stensson (Natt och Dag), who was a knight, Lawspeaker of Närke and Councillor of the Realm, and died circa 1450. The family again split in two after Bengt Stensson's grandson Johan Månsson (Natt och Dag), with one line descending from Johan's elder son Måns Johansson and the other from his younger son Åke Johansson. Åke's great-grandson and namesake Åke Axelsson (Natt och Dag) lived 1594-1655. He served as a Councillor of the Realm and also as Marshal of the Realm, and on 20 April 1652 he was ennobled by Queen