Vikings in Iberia
Vikings returned to Galicia in 859, beginning what seems to have been a three-year campaign, during the reign of Ordoño I of Asturias. The main source for these events are Arabic histories compiled by Ibn Ḥayyān in the eleventh century, though some near-contemporary Latin sources also mention the events, and later Latin sources offer more elaborate, but less reliable, accounts. In the assessment of Ann Christys, what can be known about the Viking raids on Iberia in 859-61 is thatThe expedition of 859–861, like that of 844, seems to have involved a single band of adventurers. Returning to the scene of Viking incursions in northern Iberia and al-Andalus, but meeting with little success, they sailed on to raid targets on the shores of the Mediterranean. Here they may have taken captives for ransom or to trade as slaves. Vikings seem to have over-wintered in Francia, perhaps waiting on the northern shore of the Mediterranean for favourable tides and currents to exit the sea through the Straits of Gibraltar. They may even have sailed to Italy, Alexandria and Constantinople.Some historians have given credence, however, to a range of accounts in late sources about raids in this period as evidence for this Viking incursion. Yet different sources mention different figures; not all potentially relevant raids recounted were necessarily by Vikings; and the sources are likely more to reflect the political context in which they were composed than actual events in 859-61. For example, on the basis of an account by Al-Bakrī it has been supposed that in 859 or 860, Vikings sailed through Gibraltar and raided the little Moroccan state of Nekor, and defeated a Moorish army. But there is no evidence that the raiders in question were Vikings. Likewise, the raiders have been identified as the legendary Hastein and Björn Ironside, but this is based on modern extrapolation from already altogether unreliable medieval sources. There was a well-attested raid on Constantinople in 860, which may have been by Vikings and which has been associated with the raids on Iberia, but there is no evidence that the raid on Constantinople was by the same people who were active in the western Mediterranean at the time. Moreover, it is plausible that the Constantinople raiders came from the north by the river-routes running from the Baltic into the Black Sea (known in Old Norse as the "Austrvegr"). A story about an attack in the period 859-61 on "Banbalūna" (which could mean modern Pamplona but also the whole kingdom of Navarre), again, may or may not reflect activities of Vikings.
History of Limerick
The earliest record of vikings at Limerick is in 845, reported by the "Annals of Ulster", and there are intermittent reports of vikings in the region later in the 9th century. Permanent settlement on the site of modern Limerick had begun by 922. In that year a Viking jarl or prince called Tomrair mac Ailchi—Thórir Helgason—led the Limerick fleet on raids along the River Shannon, from the lake of Lough Derg to the lake of Lough Ree, pillaging ecclesiastical settlements. Two years later, the Dublin vikings led by Gofraid ua Ímair attacked Limerick, but were driven off. The war between Dublin and Limerick continued until 937 when the Dubliners, now led by Gofraid's son Amlaíb, captured Limerick's king Amlaíb Cenncairech and for some reason destroyed his fleet. However, no battle is actually recorded and so a traditional interpretation has been that Amlaíb mac Gofraid was actually recruiting Amlaíb of Limerick for his upcoming conflict with Athelstan of England, which would turn out be the famous Battle of Brunanburh. The 920s and 930s are regarded as the height of Norse power in Ireland and only Limerick rivalled Dublin during this time.