History and settlement
The earliest available documents on the history of the Comoros date only from the year 1500, when the Portuguese and Arab navigators from Persia set foot on the islands.
It is difficult to date precisely the arrival of the first inhabitants, but it is likely that the population of African origin preceded the arrival of the Arabo-Shirazi and the Malagasy.
It seems likely that the wave of African population originating from the east coast of Africa reached the Comoros during the Iron Age, between the 5th and 10th centuries.
Unfortunately, little is known about this period. Were they the first? Were they preceded by Proto-Malagasy people on their way to Madagascar? Or by those seafaring traders of indeterminate origin later known as Antalots? In any case, the chronicle of Saïd Bakari, which recounts the origin of the sultanates of Grande Comore, suggests that the first arrivals came from Africa.
The Kilwa Chronicle, for its part, dates the arrival of the first Arab-Shirazi to the 11th century in Anjouan (Kilwa was established as a sultanate by a Persian prince from Shiraz in 975). Ocean currents and monsoon patterns also make the passage of people from Southeast Asia plausible in earlier times.
Some very ancient elements of Comorian civilization probably come, directly or indirectly, from this region (outrigger canoe, betel, coconut tree and perhaps rice).
In any case, it was probably only from the 16th century onwards that the arrival in the Comoros of a new wave of Arab-Shirazi (coming either directly from "Shiraz," a term actually referring to the Persian Gulf, or from the east coast of the continent called Zanj or Mrima) profoundly transformed existing society, with the newcomers dominating the traditional chiefs and/or forming alliances with them through marriage. Written sources, manuscripts in Arabic, Swahili, or Comorian written in Arabic script, date from this period and allow us to reconstruct genealogies.
We also have accounts from European navigators: the Portuguese even settled on Grande Comore from 1500 to 1505, triggering a mass exodus of the inhabitants of Grande Comore to other islands, particularly to Mchambara (which would become M'zamboro) in the northwest of Mayotte. The archipelago was now organized into sultanates and society divided into more or less rigid classes (wakabaila: the "nobles"; a class of free men: farmers, herders, fishermen; and slaves).
Islamization became more widespread: the first stone mosque in Mayotte was built in Chingoni in 1566, and the first mosque in Anjouan, in Sima, around the same time. It was also in the 16th century that a group of Sakalava Malagasy settled in southern Mayotte. From this period onward, an Arab-Shirazi population in the north and a Sakalava population in the south coexisted on the island, all against a backdrop of African origin.
(Source: beit-salam, comorosdiscover, daharicomores, wikipedia)
https://www.comores-tourisme.net/Histoire_et_peuplement_des_Comores.html
