Reunion was once a French colony. In 1848 the French abolished slavery so they needed a new source of cheap labor for their plantations. They looked to India, specifically Tamil Nadu and Pondicherry, the latter with French influence.
Tamil speakers, both Hindu and Christian, began to work on these plantations. There were many difficulties for this industry. There were the forces of nature that sometimes tore plantations apart. At one time Reunion was taken by British forces.

Today the culture of Reunion is what we might call a hybrid culture. It mixes in aspects of various cultures, and even the dominant French language is Creolized. Most likely the Tamil language is different in Reunion than it is in India or Sri Lanka.

Some are nominally Christian but incorporate Hindu practices. Most are Roman Catholic. Tamil speakers are more Christianized in Martinique than they are in Reunion.

Tamil speaking Christians need biblical materials and Bible teachers. They need to get their faith centered on Jesus Christ.

Pray for Tamil speaking disciplers to disciple others in Reunion.
Pray for churches in Reunion to center on Jesus Christ and the teachings of the Bible.
Pray for the Holy Spirit to bring revival fire to the French speaking world.

Scripture Prayers for the Tamil (Christian traditions) in Reunion.

https://en.wikipedia.org/wiki/R%C3%A9unionnais_of_Indian_origin
https://tamilspast.blogspot.com/2015/09/the-tamils-of-reunion-and-their-hybrid.html