 If he did indeed leave Ireland, Amlaíb had returned by 857 at the latest when he and Ímar fought against Máel Sechnaill, overking of the Southern Uí Néill, and a group of Vikings sometimes known as the Norse-Irish.Máel Sechnaill was the most powerful king in Ireland at the time and his lands lay close to the Viking settlement of Dublin.The fighting began in the previous year