Many believers are found in the Majority World. And many migrate.
Many people from unreached people groups migrate as well. And even many believers who migrate are representatives of unreached people groups.
If you need an opportunity to teach your people about the migration of the nations, then know that December 18 is International Migrants Day.
Strangers Next Door was written to help you understand what the Divine Maestro has been doing through the orchestration of the movement of the nations. Welcoming the Stranger is another excellent book to assist you and your church on immigration matters.