As far as the Middle East goes, Christian dialogue with rest of the world for as long as 500 to 1500 years. The caliphs wanted it that way, and the Christian communities there became of local significance only. There was no global outreach even possible for them, no communication getting out, and no communication coming in.
And now, starting with perhaps the Armenian genocide, Christianity in the ME is being eradicated before our very eyes. Turkey even a hundred years ago had a sizable Christian presence. Now the state is 98 percent Muslim. Bethlehem is now a Muslim city. The Christians of Iraq and Syria are under genocide conditions, and the Copts are but one election away from a MB victory and the promised deadly retaliation for their lack of submission in the Sis restoration.
The ME is the birthplace of Christianity. From Turkey to Egypt, the ME was the original centre of the Christian universe. Rome was the backwater, and the powerful bishoprics of Alexandria and Jerusalem and Constantinople vied with one another for hegemony among Christians.
But it really is not on account of trolls that people no longer recognize this as such. It is on account of Christians in the ME being cut off and subjugated, and now eradicated, that people have no good inkling that these Christians even exist.
They say that 10 percent of Syria is, or was, Christian, but only a fraction of a percentage of the refugees escaping from Syria are Christian.
We can only hope that those percentages change pretty soon, or the most likely scenario is that even more people will have nary an inkling that the ME is a source of Christians, because those kinds of Christians will cease to even exist, soon enough.