The Unreached are the people of the world who have no chance of hearing the good news about Jesus Christ.
They have no churches nearby, no bibles in their language and no witness that can tell them the good news about the Kingdom of God.
The bible is full of scriptures talking about how God wants to reconcile all people and tribes back to Him. Missions is not a man made ministry to keep us busy, it is the command by God to see His glory cover the world as the water covers the sea.
Everyone deserves a chance to hear about Gods love. Even if you live in the middle of nowhere.
The 10/40 window refers to a geographical window extending from latitude 10°N to 40°N of the equator. These countries make up Northern Africa, the Middle East and almost all of Asia.
Although countries in this window are not the only places that are home to unengaged and unreached people groups, it does give an impression of the cultures, societies and religious groups that have not yet had the opportunity to hear about their Saviour.