Where Are The Tribulation Saints Coming From ?

Have you ever wondered where the Tribulation Saints come from at the very beginning of the Tribulation?
We know that during that time period that some will come to know Jesus as the Christ and accept the gift of salvation.

But at the very beginning, where are these believers coming from?

There are 2 main thoughts on this.
One is that, the Christians existing now experience some part of what is known as The Tribulation
They are the Saints
The believers in Christ during the Tribulation.
Thus, we in Christ, right now, the Saints will eventually become, Tribulation Saints.

The other main thought is that after the Rapture of the Church, there will be many Jews and Gentiles that come to know Christ.
And many want to know, just how could this possibly happen?