The ME started falling behind the west in about the 1400's. The west started adding to their misery just after WW1 after we redrew their boundaries according to how we wanted the countries to align.
When you say "falling behind" you mean, militarily.
Which of course translates to economically, since the West used it's military power to take and exploit.
But then the game changer, oil.
That is when the modern history of the ME begins. When it is discovered it contains incredible wealth.
Then suddenly places like England are very interested and begin poking their heavy hand into the region with a purpose.
The madness culminates with the removal of the elected leader of Iran. That event very much shapes the current picture of the ME today.