Go to 1:19 and you will see the global population distribution at the time of the earliest Church.
The total population is estimated at 173 million.
People have worried about the fact that the Americas were unknown at that time including to the apostles who were commissioned to evangelize the world and that the people of the Americas simply perished without ever hearing the gospel. The total population of the Americas at that time is estimated to have been only 7 million though.
The total population of Africa outside of the Nile area was about 5 million. In South East Asia, Indonesia and Australia there were about 5 million.
90 percent of the world's population was found in Europe, the middle East including Egypt, India, China and Japan.
The Roman empire which can be seen in red in the video was evangelized quite rapidly and scholars speculate that Paul did get as far as Spain at the Western end of the empire. The rest of continental Europe followed. The apostle Thomas is said to have reached India but probably not the Ganges plain where the majority of the people were found. Noone reached eastern China. Those two areas made up at least half the world's population at that time.