For then shall be great tribulation, such as was not since the beginning of the world to this time, no, nor ever shall be. (Matthew 24:21)
For [in] those days shall be affliction, such as was not from the beginning of the creation which God created unto this time, neither shall be. (Mark 13:19)
And at that time shall Michael stand up, the great prince which standeth for the children of thy people: and there shall be a time of trouble, such as never was since there was a nation even to that same time: and at that time thy people shall be delivered, every one that shall be found written in the book. (Daniel 12:1)
For thus saith the LORD; We have heard a voice of trembling, of fear, and not of peace. Ask ye now, and see whether a man doth travail with child? wherefore do I see every man with his hands on his loins, as a woman in travail, and all faces are turned into paleness? Alas! for that day is great, so that none is like it: it is even the time of Jacob’s trouble; but he shall be saved out of it. (Jeremiah 30:5-7)
Based on the passages above, the second half of the 70th week of years will see a time of great tribulation unlike any other in history for Israel. Followers of Jesus Christ will also be impacted since we have been grafted into the root of the olive tree that represents God.
For if the firstfruit [be] holy, the lump [is] also [holy]: and if the root [be] holy, so [are] the branches. And if some of the branches be broken off, and thou, being a wild olive tree, wert graffed in among them, and with them partakest of the root and fatness of the olive tree; Boast not against the branches. But if thou boast, thou bearest not the root, but the root thee. Thou wilt say then, The branches were broken off, that I might be graffed in. Well; because of unbelief they were broken off, and thou standest by faith. Be not highminded, but fear: For if God spared not the natural branches, [take heed] lest he also spare not thee. Behold therefore the goodness and severity of God: on them which fell, severity; but toward thee, goodness, if thou continue in [his] goodness: otherwise thou also shalt be cut off. And they also, if they abide not still in unbelief, shall be graffed in: for God is able to graff them in again. For if thou wert cut out of the olive tree which is wild by nature, and wert graffed contrary to nature into a good olive tree: how much more shall these, which be the natural [branches], be graffed into their own olive tree? (Romans 11:16-24)
This great tribulation is a result of the conflict between the woman in heaven and the great red dragon.
When Jesus begins to destroy Antichrist’s kingdom from Heaven there will be great tribulation for the people of Antichrist’s kingdom. In that sense, great tribulation extends until Jesus returns.
Immediately after the tribulation of those days shall the sun be darkened, and the moon shall not give her light, and the stars shall fall from heaven, and the powers of the heavens shall be shaken: And then shall appear the sign of the Son of man in heaven: and then shall all the tribes of the earth mourn, and they shall see the Son of man coming in the clouds of heaven with power and great glory. (Matthew 24:29-30)