AHC: Make Madagascar a Portuguese colony during the 1800s

At one point, the Portuguese did discover Madagascar by Bartolomeu Dias's younger brother, what would happen if the Portuguese managed to establish a colony in Madagascar or at least made a trading post?

What if they forced the Imerina Kingdom to become a Protectorate through several wars like France did, or if the Portuguese made several attempts to take Madagascar through the Berlin Conference of 1881?

How would this affect the rest of history after 1900s?
 
At one point, the Portuguese did discover Madagascar by Bartolomeu Dias's younger brother, what would happen if the Portuguese managed to establish a colony in Madagascar or at least made a trading post?

What if they forced the Imerina Kingdom to become a Protectorate through several wars like France did, or if the Portuguese made several attempts to take Madagascar through the Berlin Conference of 1881?

How would this affect the rest of history after 1900s?

By the beginning of the 16th century Zanzibar was controlled by the Portuguese, this coincides with a large expansion of Zanzabari/Arabo-Swahili in the Northwest Coast.

The Portuguese were worn thin and left the people largely to themselves. But say instead the Portuguese and more importantly the Luso-Eurafricans of Mozambique and the East African Coast fled en masse to the "Swahili" Coast of Madagascar and pulled a Thomas Tew all along the coasts?

You'd make a very strong case for a luso-fication and firm grip with the resultant Zana-Malatta chieftains unified under a single flag.


Also.

The Imerina were irrelevant until the late 18th century and only were able to dominate with the introduction of Western weaponry with a French castaway.

Before that it was the West Coast/East Coast that dominated and enslaved inland groups for Arab and Western Slave trade.
 
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