The 10/40 Window is a region that spans parts of Africa and Asia, containing the greatest concentration of unreached people groups in the world. This area is known for its high population density of unreached peoples and limited access to Christian missionaries.

Because it can go places often unreached by vehicles and it can get there faster

Pondicherry Institute of Medical Sciences's motto is 'To reach the unreached'.

Christianity and he preached about salvation and testified about his own experiences with God boldly to help the unreached souls to become saved.

There are MANY Christian missionaries in Papua, New Guinea as that area has quite a few unreached tribes still (as of 2009). That is just one example. There are unreached people groups in a lot of countries, some of which have missionaries presently working to bring them the Gospel, some don't. See the Related link below for more information.