A thrall was a slave or serf in Scandinavian lands during the Viking Age. The status of slave contrasts with that of the freeman and the nobleman.
Erling Skjalgsson sets his thralls to day-work (Erik Werenskiold, 1899)
Beowulf's thrall steals the golden cup from the dragon (Joseph Ratcliffe Skelton, 1908)
Slavery had already existed in Ireland for centuries by the time the Vikings began to establish their coastal settlements, but it was under the Norse-Gael Kingdom of Dublin that it reached its peak, i
Thrall
…of the most important purposes of the Viking raids. People taken captive during the Viking raids across Europe could be sold to Moorish Spain via the Dublin slave trade or transported to Hedeby or Brännö and from there via the Volga trade route to present day Russia, where slaves and furs were sold to Muslim merchants…
Viking Age slave chain (found in Germany)
As a young man, Saint Patrick was kidnapped by Irish pirates, transported to Ireland, and sold as a slave.
Slaves having a stick fight. A white indentured servant is standing on the left.