One of the most important passages in understanding coming events and the clarification of ‘Last Things’ is found in Daniel 9:21-25. A couple important points:
1) The ‘weeks’ determined here in Daniel 9 are periods of 7 years.
2) Much of this prophecy has been fulfilled already in great detail. In fact we find that 69 of the 70 ‘weeks’ (or 483 of the 490 years) have been fulfilled already.
3) The tribulation period of 7 years is the fulfillment of this last period or week of prophecy towards the nation of Israel. God will be dealing directly with the nation of Israel during this period of 7 years.
4) The Church has been raptured/removed before this period. The Church age has ended and the final 7 years of God’s dealings with the Nation of Israel have begun with the removal of the Church. This is the pre-tribulation position and has the strongest Biblical support.