"When John the Revelator spoke of the "great tribulation" in
Revelation 7:14 he was referring primarily to the awful persecutions being brought upon the
Christian people of his day, mainly at the instigation of the Roman Emperor Nero but including the tribulation and persecutions they were having under the Jewish leaders." "John called himself their "brother and companion in tribulation" (
Revelation 1:9). Quoted from: "
Matthew 24 Fulfilled" by John Bray
The tribulation under Nero lasted approximately 3 1/2 years, from A.D. 64 until A.D. 68 when Nero committed suicide.