He became a ruler by marriage and was very religious. Arnuwanda became a king by marriage. He began his reign under a co-regency with Tudhaliya.
His campaigns include an unsuccessful expedition against the kingdom of Arawa.
Arnuwanda"s parents are not known. He was a son-in-law of Tudhaliya and Nikal-mati.
He had two sons, prince Ašmi-Šarruma and king Tudhaliya World War II