Depending on your definition of “the region” I think this isn’t really supportable. Iran itself has had long periods of what passed for stability at the time.
According to Wikipedia History of Ancient Iran/Persia we can tote up the durations of specific empires:
[ul]
[li]Median and Achaemenid Empire (650 BC–330 BC): 320 years[/li][li]Seleucid Empire (312 BC – 63 BC): 375 years[/li][li]Parthian Empire (248 BC — AD 224)*: 472 years[/li][li]Sassanid Empire (224 – 651): 427 years[/li][/ul]
*Notice the overlap between Parthian and Seleucid; both empires controlled parts of what we’d call Persia/Iran and despite warring with each other both have been considered historical Persia.
Later on, Iran became a monarchy ruled by a shah, or emperor, almost without interruption from 1501 until the 1979 Iranian revolution: 478 years.
United States from Declaration of independence to right now: 236 years.
I suppose you can say that dynastic turnover in those empires was “instability” but you might then have to count elections in the US. I suppose you could say “but there were a lot of wars with their neighbors…” but I’m not sure that counting periodic wars with neighbors as instability would define the US as “stable.”
That’s at least five periods of stability and national identity longer than the entire existence of the United States…entirely skipping over the question of whether the early Islamic periods count. Two of those periods were TWICE as long as the US has existed…each.
If you’re going to define “the region” as “the whole Middle East” then we’ve got to expand our comparison to “North America” or “Europe,” neither of which have fared particularly well at avoiding dynastic upheaval, regime change, or war over the last 5,000 years.
I know “The Middle East” (meaning Palestine and surrounding areas) has seen a whirlwind of particularly savage fighting, uprisings, terror, and political conflict since…let’s see…probably since the collapse of the Ottoman Empire some time around 1918, depending on how you count it. But that isn’t really “the last 5,000 years.”