Somdet Phra Chairachathirat (commonly shortened to Chairacha) reigned 1534–1546 as King of the Ayutthaya kingdom of Siam. His reign was remarkable for the influx of Portuguese traders, mercenaries, and early Modern warfare technology. When Phra Chairaja died he had two sons by Thao Sisudachun, named Prince Keofa or Yodfa, and Prince Sisin.