Answer by taking a quote from the following article:

Saint Isidore of Seville (; Latin: Isidorus Hispalensis; c. 560 - 4 April 636), a scholar and, for over three decades, Archbishop of Seville, is widely regarded as the last of the Fathers of the Church, as the 19th-century historian Montalembert put it in an oft-quoted phrase, "The last scholar of the ancient world." At a time of disintegration of classical culture, and aristocratic violence and illiteracy, he was involved in the conversion of the Arian Visigothic kings to Catholicism, both assisting his brother Leander of Seville, and continuing after his brother's death. He was influential in the inner circle of Sisebut, Visigothic king of Hispania. Like Leander, he played a prominent role in the Councils of Toledo and Seville.

Isidore was one of the last of the ancient Christian philosophers; he was the last of the great Latin Church Fathers and was contemporary with Maximus the Confessor. Some consider him to be the most learned man of his age, and he exercised a far-reaching and immeasurable influence on the educational life of the Middle Ages. His contemporary and friend, Braulio of Zaragoza, regarded him as a man raised up by God to save the Iberian peoples from the tidal wave of barbarism that threatened to inundate the ancient civilization of Hispania.  The Eighth Council of Toledo (653) recorded its admiration of his character in these glowing terms: "The extraordinary doctor, the latest ornament of the Catholic Church, the most learned man of the latter ages, always to be named with reverence, Isidore". This tribute was endorsed by the Fifteenth Council of Toledo, held in 688.  Isidore was interred in Seville. His tomb represented an important place of veneration for the Mozarabs during the centuries after the Arab conquest of Visigothic Hispania. In the middle of the 11th century, with the division of Al Andalus into taifas and the strengthening of the Christian holdings in the Iberian peninsula, Ferdinand I of Leon found himself in a position to extract tribute from the fractured Arab states. In addition to money, Abbad II al-Mu'tadid, the Abbasid ruler of Seville (1042-1069), agreed to turn over St. Isidore's remains to Ferdinand I.  A Catholic poet described al-Mutatid placing a brocaded cover over Isidore's sarcophagus, and remarked, "Now you are leaving here, revered Isidore. You know well how much your fame was mine!" Fernando had Isidore's remains reinterred in the then-recently constructed Basilica of San Isidoro in Leon.  Isidore was canonised a saint by the Roman Catholic Church in 1598 by Pope Clement VIII and declared a Doctor of the Church in 1722 by Pope Innocent XIII. Many of his bones are buried in the cathedral of Murcia, Spain.

In what forms did his Veneration take place?
found himself in a position to extract tribute from the fractured Arab states.