Final answer:
By the 12th century, the Maldives had adopted Islam, which came with trade and the spread of Sufism throughout the Indian Ocean region.
Step-by-step explanation:
The religion that the Maldives had adopted by the 12th century was Islam. As Islam spread across the Indian Ocean region through peaceful conversion and trade, Sufi missionaries also played a pivotal role in introducing the faith to various cultures. By the early 1600s, Islam had become the dominant religion in the Indian Ocean, with significant presence already established by the 13th century in Southeast Asia. The Maldives, due to its strategic location within this region, was also influenced by these waves of Islamic expansion and had embraced Islam by the 12th century.
The Maldives, being situated just north of the Equator and close to India, were part of the wider Indian Ocean trading world that saw the spread of Islam. Islam came to dominate the socio-cultural landscape of the Maldives, influencing its history and development, which continues to this day as the Maldives maintains a majority Muslim population.