In September 1190 Richard and Philip arrived in Sicily. After the death of King William II of Sicily his cousin Tancred had seized power and had been crowned early in 1190 as King Tancred I of Sicily, although the legal heir was William's aunt Constance, wife of the new Emperor Henry VI. Tancred had imprisoned William's widow, Queen Joan, who was Richard's sister, and did not give her the money she had inherited in William's will. When Richard arrived he demanded that his sister be released and given her inheritance; she was freed on 28 September, but without the inheritance. The presence of foreign troops also caused unrest: in October, the people of Messina revolted, demanding that the foreigners leave. Richard attacked Messina, capturing it on 4 October 1190. After looting and burning the city Richard established his base there, but this created tension between Richard and Philip Augustus. He remained there until Tancred finally agreed to sign a treaty on 4 March 1191. The treaty was signed by Richard, Philip and Tancred. Its main terms were:  Joan was to receive 20,000 ounces (570 kg) of gold as compensation for her inheritance, which Tancred kept.  Richard officially proclaimed his nephew, Arthur of Brittany, son of Geoffrey, as his heir, and Tancred promised to marry one of his daughters to Arthur when he came of age, giving a further 20,000 ounces (570 kg) of gold that would be returned by Richard if Arthur did not marry Tancred's daughter.  The two kings stayed on in Sicily for a while, but this resulted in increasing tensions between them and their men, with Philip Augustus plotting with Tancred against Richard. The two kings finally met to clear the air and reached an agreement, including the end of Richard's betrothal to Philip's sister Alys (who had supposedly been the mistress of Richard's father Henry II).

Answer this question "What happen in Sicily" by extracting the answer from the text above.
After the death of King William II of Sicily his cousin Tancred had seized power and had been crowned early in 1190 as King Tancred I of Sicily,