The Lievens (Latvian Līveni; Swedish Liewen) are one of the oldest aristocratic families of Baltic Germans. Caupo's grandson, Nicholas, was the first to spell his name Lieven.
They claim descent from Caupo of Turaida (Latvian, Kaupo), the Livonian quasi rex who converted to Christianity in 1186, when Bishop Meinhard attempted to Christianize the region. Henrici Chronicon Lyvoniae tells that Caupo in winter 1203-1204 went to Rome with Theodoric, a Cistercian Monk (who was to become the founder of the Swordbrothers, then the first bishop of Estonia). They were received by the Pope Innocent III who backed up their plans to Christianize Livonia.
According to feudal records, the Lieven ancestor Gerardus Līvo (1269) and his son Johannes (1296) entered service as vassals to the archbishop of Rīga. One of Caupo's daughters married an ancestor of the barons, then Earl Ungern-Sternberg.
Reinhold Liewen, the Swedish governor of Oesel (Saaremaa), in 1653 was made a baron together with his brother, whose son Lieutenant-General Baron Hans Heinrich von Liewen accompanied Charles XII in all his campaigns and expeditions. Among Reinhold's descendants, one branch settled in Courland and was recognized in 1801 as in the Holy Roman Empire. Johann-Christoph von Lieven was the first member of the family to gain distinction in the Russian service: he served as Governor of Arkhangelsk under Catherine the Great and as General of Infantry under Emperor Paul.