According to Canggal inscription (dated 732 CE), the island of Java had long been under the rule of this wise and virtuous king.
Amid a period of violence and confusion Sanjaya, son of Sannaha (the sister of Sanna) ascended to the throne, and established the Kingdom of Mataram.
[1][2] He was named as Prabu Sanna or Bratasena in Carita Parahyangan (a book composed around late 16th-century CE).
According to Carita Parahyangan, Sanna was the King of Galuh that was usurped by his cousin, Purbasora.
So, to avenge his father's defeat, Sanjaya attacked Galuh with a special force and killed Purbasora along with his family.