So, I'm planning to start a new TL, using a limited first-person (OC) narrative this time, based upon this premise- in the mid 11th century, a Vellalar prince looking to gain influence and power in the Imperial Chola court funds and organizes a small colonial expedition to search for new unclaimed lands south-east of Java; first establishing a trade post on the island of Sumba in passing, but then pushing onward, bypassing the Savu Sea, and discovering North-Western Australia in the process (making landfall somewhere along the coast of the Joseph Bonaparte Gulf).
And over the course of the next few decades, he subsequently follows the standard modus-operandi employed by the Vellalar across South India and Sri Lanka- in which settlers would move out into virgin land, which had previously been used by hunter gatherer or tribal peoples for slash and burn agriculture or for hunting, and convert it into prime agricultural land (with 'Vellalar' being an honorific title, granted to a select few people who would organize such raids and establish such settlements, with the chiefdoms themselves also known as 'Vel', and the title of 'Vellalar' historically being restricted to the heads of these villages, or the aristocratic lineages of their founding chiefs).
BTW, the first-person narrator isn't going to be the aristocratic leader of the expedition himself, but instead a member of one of the South Indian trade guilds, the Setti-Guttas, who were warriors first and merchants second, and were often hired by traders to ensure protection of itinerant groups and caravans, as well as to ensure the safety of trading settlements. How plausible does the premise of this TL sound to you? And how successful could you envision the Tamil Chola settlement of Northern Australia being ITTL?