You will be given a definition of a task first, then some input of the task.
In this task, you're given a passage, further information available on a particular linked term from the statement, and a question. Your job is to generate the answer to the question by using the information provided. If there is no clear answer obtainable, output 'none'.

Passage: At the time of his accession, Theophilos was obliged to wage wars against the Arabs on two fronts. Sicily was once again invaded by the Arabs, who took Palermo after a year-long siege in 831, established the Emirate of Sicily, and gradually continued to expand across the island. The defence after the invasion of Anatolia by the Abbasid Caliph Al-Ma'mun in 830 was led by the Emperor himself, but the Byzantines were defeated and lost several fortresses. In 831 Theophilos retaliated by leading a large army into Cilicia and capturing Tarsus. The Emperor returned to Constantinople in triumph, but in the autumn he was defeated in Cappadocia. Another defeat in the same province in 833 forced Theophilos to sue for peace (Theophilos offered 100,000 gold dinars and the return of 7,000 prisoners), which he obtained the next year, after the death of Al-Ma'mun.
Link Information: After the conquest of Sicily, the Normans removed the local emir, Yusuf Ibn Abdallah from power Question: Who was the last leader of the the country that was established after the year-long siege in 831?
Output:
Answer: Yusuf Ibn Abdallah