Another aspect is the overseas Hindu teachings.
Traders from India have been connected with Indonesia for over 2000 years. Until the 1500s there were Hindu-Buddhist communities and kings, with a retreat from Islam to the island of Bali where the last Hindu-Buddhist kings were shot by the Dutch in 1906, The kings merged Hindu with Buddhist teachings and with Javanese traditions and then with Balinese traditions. Old Java language was about 25% Sanskrit words, as recorded in religious texts. Bali today is viewed as mainly Hindu in faith.
It seems that Javanese ships reached Australia with a date of the 13th century as likely for one contact. The syncretic teachings evidently were further blended with Aboriginal traditions and some Skt-Javanese words were adopted. So depending on your standards of authenticity, 'Australia' possibly was a Hindu-Buddhist area.