Read about the Church of the East -- the Assyrian church (a.k.a. the Holy Church of the East) - in the 8th century this had more people and a wider population than the church in Europe.
The missionaries converted people and preached and pastored to people in Yemen, Syria, Iraq, Iran, India, all the way to Mongolia and western China.
What happened to this? Islam -- Timur-e-Lang, the greatest jihadi warrior killed most -- he was a master of genocide, having killed 5% of the world's population (more than GEnghis khan, Stalin, Mao etc.)
The largest Christian group today is the Syriac Church
And the word of God today is by Christians of different ethnic backgrounds.
Christians as you put it, were killed off by Timur in that region. Hence, since then Europe has been the standard bearer, up until the early 20th Century.