Sadu (Proto-Austronesian) comes from Pali sādhu, from Sanskrit साधु, from Proto-Indo-Aryan *sáHdʰuṣ, from Proto-Indo-Iranian sáHdʰuš, from Proto-Indo-European séHdʰ-u-s, from Proto-Indo-European -us — Forms adjectives from Caland system roots.
Ancestry of “Sadu”, step by step
Sadu traces back through 3 separate lines of ancestry.