According to Totally Timelines, Sigtryggr was born in Dublin around the year 895 and he was the grandson of Viking warlord Imar.
Imar is believed to have been compared to Ivar the Boneless, who went to Ireland and later disappeared from historical records.
Sigtryggr is thought to have been 32 when he died, and he had spent his life trying to discover where he belonged after two Irish chieftains kicked him out of Dublin.
Sigtryggr and his brother Ragnall led separate raids in Ireland, and later Northumbria, where Ragnall was ruler. After he died, Sigtryggr took up the role as the Northumbrian leader.
He did not get on well with king Edward the Elder, and started taking land owned by Edward. When Edward died, Sigtryggr came to an agreement with his heir Aethelstan, and for a time reverted to Christianity.
But in the year 926, it is believed he renounced the religion and went back to Paganism. He died the following year in 927.