The Roman Empire showed a dislike of this area, and it is believed that Amoroto was populated by whose main occupation was cattle raising.
In his work "Historia de Vizcaya", Iturriza mentions that the town of Amoroto used to be called Amoredo. It seems that the local population settled there between
centuries. The first precise data goes back to 1325, and according to it, Amoroto was subject to Andra Mari´s Basilica in Lekeitio, as it had to hand over a third of the tenths that it produced to the Basilica. Thus, although in the XIVth century the town was under the rule of Lekeitio, it was important enough as to have .The demographic growth and the economic power brought by the Middle Ages provoked the desire in the inhabitants of Amoroto to become independent. The town applied for a separation from the Basilica of Andra Mari in 1454, but the application did not succeed
.Before
, though, Amoroto was named Royal parochial district under the rule of Adan of Yarza, and had to pay a tax of 18.000 maravedis to the Kingdom of Castille.Once independent, there was a need to organise Amoroto as an independent unit and to set
. New politicians also appeared.In the period when these changes occured, society was organised into hierarchies which were almost feudal: the system of taxes and the clergy continued, and the families of noble descent were at the top of the social pyramid (
lineage was the most powerful one in Amoroto). These families had gathered a lot of money thanks to their rights over the farms and hills, the tenths of the parochial district and so on. That was the basis of their political and economic power, and it gave them the right to claim assets in critical times. This right provoked many conflicts such as family feuds.