Cattle raids were a mainstay of Heroic Age society.
A chieftains and his war-band would raid nearby chieftains. The objective was generally to steal cattle, however pigs, horses, and other objects of value might have been stolen. The chieftain was also expected to defend his own property from theft.
There was nothing legally or morally wrong in cattle stealing. It was considered a proper royal activity.
Cattle raiding was significant for several reasons. First, the simple act of stealing from another chieftain gave him prestige. Second, any property he stole added to the chieftain's wealth while taking from his adversaries. The added property gave the chieftain more funds to spend on rewarding his warriors and paying for better bards, which in turn could improve his teulu and his kingdom.