Slavery
Slavery, a much darker part of the Viking age, was involved in raids carried out against English villages. Archaeological traces of evidence revealed periods when people were sold as slaves and held captive. Slavery, or "Thralls," as they were known in old Norse script, was also thought to be a factor in the Viking occupation of England. Slaves comprised up about ten percent of the entire Viking population.
Since Vikings were willing to do anything for money, they sold enslaved individuals to Islamic markets in return for wealth. A significant component of Viking society has always been the trafficking, exploitation, and selling of human beings. The Vikings confined the captives in cramped quarters with little food, which led to their deaths from malnutrition. Furthermore, it was certain that such individuals would never be released because they were unable to inherit anything or receive compensation. Archaeologists discovered a variety of iron shackles and collars in the locations suspected of being slave hubs in Dublin, Hedeby, and Birka, according to the journal "Slavery and Abolition." These items were used to restrain people in thralls' concentration camps.
The Vikings severely abused those who were held as slaves and referred to them as bastards, stinkers, and sluggards. Enslaved persons were killed and then left out in the open to be eaten by dogs and birds. The bodies inside the tomb were unrelated to the beheaded remains discovered inside adjacent Viking tombs. According to archeologist Elise Naumann, such bodies were proof of human sacrifices done at the time of masters' deaths. The exhumed bones showed starvation with a diet that consisted mostly of fish while the masters ate lavishly. That's all about the fifth reason why Vikings invaded England we want to mention.