Thai Sa

Sanphet IX (Thai: พระบาทสมเด็จพระสรรเพชญที่ ๙) or Thai Sa (Thai: สมเด็จพระเจ้าอยู่หัวท้ายสระ) was the King of Ayutthaya from 1709 to 1732 and the third ruler of the Ban Phlu Luang Dynasty.

King Thai Sa was born Prince Surindra (Thai: พระสุรินทรกุมาร) to King Suriyendra and his principal queen. After the death of his father in 1709 Prince Surindra was crowned as King of Siam and took the reigning name Bhumindaraja (Thai: พระภูมินทราชา). He appointed his brother Prince Voraraj as the Front Palace. The king was said to be very fond of silver barb that he forbade anyone but himself from fishing them or else they would be fined. This earned him the epithet King of the Backyard Pond or King Thai Sa.

In 1715, Nguyễn Phúc Chu the Nguyen lord who supported King Keao Fa III invaded Oudong and King Thommaracha III and Prince Ang Tong along with their families fled to Ayutthaya. King Tai Sa ordered Chao Phraya Chakri to invade Cambodia to restore King Thommarcha in 1717. The Siamese fleets suffered defeat by the Vietnamese at Banteay Mas yet on the land the Siamese were able to reach Oudong in 1718 and eliminated Vietnamese troops in the city. King Keao Fa, however, took negotiating measures and agreed to pay tribute to the Siamese court.