After the disintegration of the Western Roman Empire, the current area of Aragon was occupied by the Visigoths, forming the Visigothic Kingdom.

In the year 714 muslims from North Africa conquered the central area of Aragon, converting to Islam the ancient Roman cities such as Saraqusta (Zaragoza) or Wasqa (Huesca). It was at this time that an important Muwallad family arose, the Banu Qasi (بنو قاسي), their domains were located in the Ebro Valley between the 8th and 10th centuries. After the disappearance of the Caliphate of Córdoba at the beginning of the 11th century, the Taifa of Zaragoza arose, one of the most important Taifas of Al-Andalus, leaving a great artistic, cultural and philosophical legacy.

The name of Aragon is documented for the first time during the Early Middle Ages in the year 828, when the small County of Aragon of Frankish origin, would emerge between the rivers that bear its name, the Aragón river, and its brother the Aragón Subordán river.

That County of Aragon would be linked to the Kingdom of Pamplona until 1035, and under its wing it would grow to form a dowry of García Sánchez III of Pamplona to the death of the king Sancho “the Great”, in a period characterized by Muslim hegemony in almost the entire Iberian Peninsula. Under the reign of Ramiro I of Aragon would be extended borders with the annexation of the counties of Sobrarbe and Ribagorza (year 1044), after having incorporated populations of the historical comarca of Cinco Villas.

In 1076, on the death of Sancho IV of Pamplona, Aragon incorporated part of the Navarrese kingdom into its territories while Castile did the same with the western area of the former domains of Sancho “the Great”. During the reigns of Sancho Ramírez and Peter I of Aragon and Pamplona, the kingdom extended its borders to the south, established threatening fortresses on the capital of Zaragoza in El Castellar and Juslibol and took Huesca, which became the new capital.

This leads to the reign of Alfonso I of Aragon that would conquer the flat lands of the middle Ebro Valley for Aragon: Ejea de los Caballeros, Valtierra, Calatayud, Tudela and Zaragoza, the capital of the Taifa of Saraqusta. At his death the nobles would choose his brother Ramiro II of Aragon, who left his religious life to assume the royal scepter and perpetuate the dynasty, which he achieved with the dynastic union of the House of Aragon with the owner of the County of Barcelona in 1137, year in which the union of both patrimonies would give rise to the Crown of Aragon and would add the forces that to its they would make the conquests of the Kingdom of Majorca and the Kingdom of Valencia possible. The Crown of Aragon would become the hegemonic power of the Mediterranean, controlling territories as important as Sicily, Corsica, Sardinia or Naples.

The monarch was known as King of Aragon and also held the titles of King of Valencia, King of Majorca (for a time), Count of Barcelona, Lord of Montpellier, and (temporarily) Duke of Athens and Neopatria. Each of these titles gave him sovereignty over the specific region, and the titles changed as territories were lost and won.

According to Aragonese law, the monarch had to swear allegiance to the Kingdom’s laws before being accepted as king. Like other Pyrenean and Basque realms, the Aragonese justice and decision-making system was based on Pyrenean consuetudinary law, the King was considered primus inter pares (‘first among equals’) within the nobility. A nobleman with the title “Chustizia d’Aragón” acted as ombudsman and was responsible for ensuring that the King obeyed the Aragonese laws. An old saying goes, “en Aragón antes de Rey hubo Ley” (“in Aragon Law came before King”), similar to the saying in Navarre, “antes fueron Leyes que Reyes”, with much the same meaning.

The subsequent legend made the Aragonese monarchy eligible and created a phrase of coronation of the king that would be perpetuated for centuries:

We, who are worth as much as you we make you our King and Lord, as long as you keep our fueros and liberties, and if not, not.

— The Chustizia d’Aragón

This situation would be repeated in the Commitment of Caspe (1412), which avoids a war that had dismembered the Crown of Aragon when a good handful of aspirants to the throne emerged after the death of Martin of Aragon a year after the death of his first-born, Martin I of Sicily. Ferdinand I of Aragon is the chosen one, of the Castilian House of Trastámara, but also directly connected with the Aragonese king Peter IV of Aragon, through his mother Eleanor of Aragon.

Aragon is already a large-scale political entity: the Crown, the Cortes, the Deputation of the Kingdom and the Foral Law constitute its nature and its character. The marriage of Ferdinand II of Aragon with Isabella I of Castile, celebrated in 1469 in Valladolid, derived later in the union of the crowns of Aragon and Castile, creating the bases of the Modern State.