Surrounded by the lsles of Salvora, Ons, Arosa, and touristic San Xenxo, the old Celtic land of Ocobrix has been an isle until recent ages, when ocean strams created a sedimentary union with the Salnes peninsula. During the Viking Invasions, A Lanzada’s Tower was the most advanced survey point that, together with Cambados and Catoira, alerted Santiago of the enemy. In the battle of A Lanzada, the Scandinavians were defeated by the troops of Bishop Xelmirez. 

History of Viking invasions:

The Scandinavians explored the coasts of Galicia and made several incursions until reaching Corunna where they were defeated when entering the port. Reports say that "those unknown Norman people were pagan and very cruel". 

It is during this time that the legendary Bishop Gonzalo from the region of Britonia in the north of Galicia saw a large number of Viking drakkars sailing up the Masma river. The people stood round the Bishop considering him a saint. Gonzalo looked up at the sky and began to pray and asked for protection against the Vikings, when suddenly a great storm appeared, thus sinking most of the fleet. 

During the reign of Ordonno I, from 850 to 866, the Vikings carried out their first incursion in Galicia. Worried by the borders instability with Arabia in the south, the Galician bishops moved from royal Dume to Britonia. The Scandinavians entered through the Arousa estuary reaching Santiago de Compostela. A squadron of 100 Viking ships, attracted by "Galicia's Gold", attacked Iria flavia (the nearest port to the Apostolic City), plundering the village. 

When the Vikings reached Santiago they asked for gold and threatened to destroy the city. Count Petro arrived with an army and defeated the Vikings forcing them to withdraw, sinking 38 embarkations. King Ordonno decided to sent Pope Nicholas I a legation requesting a change of the Episcopal city from Iria Flavia to Santiago, where the monks would be much safer, and he also strengthend the citiy's military defenses.

The third Viking invasion took place in the year 969 when the Gallegans did not have a king and were resisting the Castillians and Arabs. The Scandinavians entered again through the Arousa estuary and headed towards the port and old Episcopal city of Iria flavia. The military bishop Sisnado was alerted in Santiago and made the invaders retreat back to Fornelos, where another Viking army counterattacked and defeated the Galicians and killed the bishop. 

Taking advantage of Galicia's internal problems, the Vikings carried out their first incursion all along the kingdom without finding any resistance and reaching the mountains of Courel. In the City of Lugo, bishop Hermenegildo succeeded in defending the town, but he could not do anything to protect the region of Bretonia and so its most important monastery was totally destroyed. 

The Scandinavians remained in Galicia and tried to convert the kingdom into a southern Normandy. Some members of the bishop and nobles' assembly agreed to this idea, which created more political instability within the kingdom. At the end, those in favour of the Union with Scandinavia were jailed and a Galician army led by count Gonzalo and Bishop Rosendo defeated and destroyed a part of the Viking fleet. 

The Vikings left Galicia and sailed towards the South carrying out some attacks from the river Douro to Santarem. The Arabs had already suffered from Viking attacks, and alerted by the creation of the Duchy of Normandy, they began to sent spies to the kingdom of Galicia so that they could get informed and prevent further Viking movements.