Setthathirath (Lao: ເສດຖາທິຣາດ; 1534–1571) or Xaysettha (Lao: ໄຊເສດຖາ; Thai: ไชยเชษฐาธิราช Chaiyachetthathirat) is considered one of the great leaders in Lao history. Throughout the 1560s until his death, he successfully defended his kingdom of Lan Xang against military campaigns of Burmese conqueror Bayinnaung, who had already subdued Xieng Mai (Chiang Mai) in 1558 and Ayutthaya in 1564. Setthathirath was a prolific builder and erected many Buddhist monuments including Wat Xieng Thong in Louang Phrabang and the That Luang in Viangchan.

Setthathirath also known as Chaiyachettha or Chaiyaset or Jayajestha, Son of the King Photisarath of Lan Xang, he was crowned King of Lanna after the death of his grandfather, Ketklao the previous King of Lanna, who died without a male heir to the throne and gave his daughter Princess Yotkhamtip in marriage to his father King Photisarath of Lan Xang.

When King Ketklao died, there was no other descendant to succeed him. High-ranking officials and Buddhist monks therefore agreed unanimously to assign the Lanna throne to Prince Setthathirath in 1546. His name was lengthened to Chao Chaiyasetthathirath.

In 1548 King Setthathirath (as King of Lanna) had taken Chiang Saen as his capital. Chiang Mai still had powerful factions at court, and the threats from Burma and Ayutthaya were growing.

After the death of King Photisararath, the nobles of Lan Xang were divided, a group supported Prince Tha Heua, another group of nobles led by Phya Vieng, Saen Marong and Kwan Darmpa supported Prince Lanchang who was born from an Ayutthayan princess. Prince Tha Heua and Prince Lanchang began to split the Kingdom up between them, when Prince Settathathirath was still in Chiang Mai. Hearing of the news of his half brothers, King Settathathirath quickly returned to Lan Xang leaving the affairs of Chiang Mai under Queen Chiraprapha's leadership, taking with him the Phra Kaew (Emerald Buddha), the Saekkam and the Sihing buddha images. He also claimed that taking the statue would allow his relatives the opportunity to venerate the image and make merit. The Nobles of Lanna felt that Setthathirath had stayed away too long, and sought another descendant of Mangrai dynasty to take the throne in 1551. They chose a distant relative of Setthathirath, the Shan Prince known as Mekuti.

...
Wikipedia