Trying to develop an ATL in which several 'lost' continents in the Indian Ocean - namely Kerguelen, Broken Ridge and the Mascarene Plateau (just east of Madagascar) - never end up being submerged and instead remain above sea level. So far, I'm on the right track in terms of determining climatic zones and flora/fauna for each of them, and have established that the Mascarene Islands will be inhabited by Austronesians whilst Kerguelen remains undiscovered until the arrival of Europeans.

However, I'm struggling to work out who reaches Broken Ridge first. It looks like the climate would be favourable enough for settlement given its location, so on that basis do people think Indonesians could discover and inhabit such a land during the Middle Ages or earlier? Had a thought that it could perhaps be used as a dumping ground for prisoners, exiles and/or refugees from the Srivijaya Empire - is this realistic enough? Or is Broken Ridge simply too far away and irrelevant for something along those lines to be plausible, meaning it remains empty until the Age of Discovery and becomes the only large landmass on Earth without a pre-European population (minus Antarctica for obvious reasons)?

The Ninetyeast Ridge would mostly remain submerged in this lore, leaving only a small chain of islands poking out from beneath the sea. This largely eliminates the likelihood of prehistoric humans hopscotching their way down there.

Interested to hear people's thoughts on this.

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  • $\begingroup$ Please edit the question to limit it to a specific problem with enough detail to identify an adequate answer. $\endgroup$
    – Community Bot
    Commented Mar 22, 2023 at 3:10
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    $\begingroup$ "So long as there's something to be gained in the way of Hot and Spicy Food or Olympic Quality Athletes, then the British" - The Pub Landlord. $\endgroup$ Commented Mar 22, 2023 at 3:49
  • $\begingroup$ The South Pacific is an argument against your assumption these early colonizers wouldn't hopscotch along 90°'s islands. $\endgroup$
    – rek
    Commented Oct 14, 2023 at 18:09

3 Answers 3


Prehistoric humans had prehistoric sea levels. If the ridge's minimum height is similar to the Sundaland region, it was populated by Homo Erectus 0.5 to 2 Ma ago, like that region. If it was somewhat lower (but still high enough to create a modern-day island chain), it was probably first inhabited by early Homo Sapiens 50,000 to 150,000 years ago, like Australia. See: wikipedia for historical sea levels during the glacial period corresponding to hominin diasporas.

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  • $\begingroup$ What if the ridge doesn't reach above sea level during those glacial maximums, and therefore no island chain? $\endgroup$
    – HubbaBubba
    Commented Mar 22, 2023 at 3:45
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    $\begingroup$ @HubbaBubba If it does not reach above sea level at glacial max, then it's not above sea level now. $\endgroup$
    – Boba Fit
    Commented Mar 22, 2023 at 16:18
  • $\begingroup$ Yes, but then when the first colonial power get there, they will claim that they discovered it, kill off who ever is there, and then it may not really matter who got there first. $\endgroup$
    – Nosajimiki
    Commented Mar 22, 2023 at 19:26

The native Andamanese of Andaman and Nicobar Islands are believed to have arrived there in the Middle Paleolithic, 26,000 years ago, as part of the East-Eurasian migration—the same population that would colonize SE and East Asia. Haplogroup D1a3, out of the Indian subcontinent.

From the Anadaman and Nicobar islands it would seem a natural move south along 90°E Ridge and then Broken Ridge.


As explicitly stated by the OP, "The 90E Ridge would mostly remain submerged in this lore, leaving only a small chain of islands poking out from beneath the sea. This largely eliminates the likelihood of prehistoric humans hopscotching their way down there." As such, I'm basing my answer off of the premise that the 90E Ridge, south of the Andaman & Nicobar Islands, effectively never rises above the waves at any point ITTL, with its subduction effectively cancelling out the elevation of the Broken Ridge microcontinent.

Provided it doesn't impact human development beyond its shores any further (i.e, via the required increased volcanic activity of the Kerguelen hotspot to keep both the Broken Ridge subcontinent and the formerly conjoined Kerguelen Plateau above sea level) TTL's Broken Ridge and Mascerene Plateau micro-continents, given their respective locations, would be practically guaranteed to be colonized by the Austronesians in the course of their oceanic migrations from Taiwan, as Madagascar itself was IOTL:


For your Broken Ridge Plateau micro-continent, I'd suggest it'd be colonized by the Austronesians no more than 500-1000yrs after their colonizations of western Java and Sumatra (i.e, 500-1000BCE)- with the non-conducive trade wind directions, and distances, involved in colonizing it from SW Indonesia presenting a similar challenge to those of Guam from the Philippines (700yr delay IOTL).


With this also corresponding to the rough timeframe in which the Austronesians appear to have first conveyed black rats to the Cocos Islands, which'd be en-route to said micro-continent). And at the very latest, your Broken Ridge continent'd be getting colonized by the Austronesians around the same time that Madagascar got colonized by them IOTL (with TTL's Madagascar probably getting colonized at least 500yrs earlier than IOTL, since the Mascarene micro-continent greatly diminishes the challenge by providing a stepping stone along the way).


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