The dynasty is sometimes called the Ulfinger, after Estrid's husband, Ulf Jarl.

[3] The name of the Estridsen dynasty recalls their acquisition of the Danish crown through the marriage of Ulf the Earl to Estrid Svendsdatter of the House of Knýtlinga, daughter of Sweyn Forkbeard and sister of Cnut the Great.

Later genealogies (introduced by the Danish historian Jakob Langebek in the 18th century)[4] trace the family from Jomsviking leader Styrbjörn the Strong, a scion of the Swedish royal family, who in turn is given a descent from legendary King Sigurd Hring, regarded as mythical by most modern historians (no actual sources mention such an ancestry).

Reliable ancestry traces back no earlier than Ulf's own father, the obscure Thorgil Sprakling and grandfather Björn (in sources called Ursius), the latter thus alternatively being identified as the above Styrbjörn by Langebek.

All of the subsequent monarchs of Denmark are cognatic descendants of the House of Estridsen.