Patani has been suggested to be founded some time between 1350 and 1450, although its history before 1500 is unclear.^[74] According to the Sejarah Melayu, Chau Sri Wangsa, a Siamese prince, founded Patani by conquering Kota Mahligai. He converted to Islam and took on the title of Sri Sultan Ahmad Shah in the late 15th to early 16th century.^[75] The Hikayat Merong Mahawangsa and Hikayat Patani confirms the concept of kinship between Ayutthaya, Kedah, and Pattani, stating that they were descended from the same first dynasty. Patani may have become Islamised some time in the middle of 15th century, one source gives a date of 1470, but earlier dates have been proposed.^[74] A story tells of a sheikh named Sa'id or Shafi'uddin from Kampong Pasai (presumably a small community of traders from Pasai who lived on the outskirts of Patani) reportedly healed the king of a rare skin disease. After much negotiation (and recurrence of the disease), the king agreed to convert to Islam, adopting the name Sultan Ismail Shah. All of the sultan's officials also agreed to convert. However, there is fragmentary evidence that some local people had begun to convert to Islam prior to this. The existence of a diasporic Pasai community near Patani shows the locals had regular contact with Muslims. There are also travel reports, such as that of Ibn Battuta, and early Portuguese accounts that claimed Patani had an established Muslim community even before Melaka (which converted in the 15th century), which would suggest that merchants who had contact with other emerging Muslims centres were the first to convert to the region.

Patani became more important after Malacca was captured by the Portuguese in 1511 as Muslim traders sought alternative trading ports. A Dutch source indicates that most of the traders were Chinese, but 300 Portuguese traders had also settled in Patani by 1540s.^[74]