Princess Bejaratana Rajasuda was the only child of the King Vajiravudh of Thailand. She was a first cousin of King Bhumibol Adulyadej as well as a third cousin to Prince Bhisadej Rajani on her paternal side and third cousin of King Norodom Sihanouk of Cambodia on her maternal side.

Vajiravudh was the sixth king of Siam from the Chakri dynasty, titled Rama VI. He reigned from 1910 until his death in 1925. King Vajiravudh is best known for his efforts to create and promote Siamese nationalism. His reign was characterized by Siam's movement further towards democracy and minimal participation in World War I. He had keen interests in Siamese history, archaeology, and literature, as well as economics, politics and world affairs, and founded the country's first university, Chulalongkorn University.