Islamic rule govenrned the southern part of the Iberian peninsula for seven hundred years. In medieval history, "al-Andalus" (Arabic: الأندلس‎ ‎ ) was the name given to the parts of the Iberian Peninsula and Septimania governed by Arab and North African Muslims (given the generic name of Moors), at various times in the period between 711 and 1492.
Islamic rule governed parts of the Iberian Peninsula for more than 800 years.
The excerpt states that the total time Islamic rule governed portions of the Iberian Peninsula was 781 years. Therefore it is inaccurate to say that it lasted for more than 800 years. The model may have been confused by the different time frames given in the excerpt.