When your natural defenses are on the wrong side of the country

Explanation From Original OP:

Context : during the middle ages and after the end of arab rule over the iranian plaueto and centeral asia there was a golden age period known as the iranian intermezzo or “ the persian renaissance “ it saw the rise of the new persian language and several native iranian dynasties ( saffarids, buyids, sallarids and the samanids)

In 870s the saffarid amir yaqub ibn layth changed the official language of iran back to persian thus since for almost 200 years iran had its official language be arabic due to the umayyad caliph al marwan.

Even after the usurpation of the samanid throne by the mamluk ghaznavids in 999 AD the persian renaissance continued as the ghaznavids despite being turkic were heavily persianized in both culture and administration ( as they had adopted it from their samanid overlords) and they continued the work of the samanid, sponsoring persian scholars, poets and scientists and built a ton of libraries. They continued this even after being kicked out of iran by the Seljuks.

The same thing happened during the seljuq conquest but after the death statesman “khaje nizami al mulk” and the greatest seljuq sultan malikshah this golden age started to crumble.

The seljuks suffered a slow death and were disestablished by the kharezmshahs ( centeral asian kipchak turks, previously seljuq vassals) which saw the further decline of the period.

After the khrezmshah mohammad ii killed the mongol messengers and caused the invasion by genghis khan iranian centeral Asia and the Iranian pleuto. The mongols utterly devastated all they touched. Most of the centeral asian iranians were wiped off the map while many many cities in iran were turned to ruins.

Cities such as

Nishapur, marv, gurganji,bukhara, samarkand, balkh, isfahan, Rey, Hamadan, ardebil, maragha, qazvin especially.

From 1220s to 1330s the mongols rulled iran and after they collapsed in the lamest way possible iran had another wave of sorta native dynasties.

The mozzafarids in south ( possibly arabs)

Qara qounlu in the north west ( turkomans from the mongol period)

And sarbadars in the north east ( persians)

Two decades after the collapse of the mongols the savage conquerer tamerlane set his eyes on Iran. Yet again he devestated the iranian plaueto and famously in isfahan and shiraz made mountain of human heads to discourage rebellions.

These two invasions irreversibly damaged iran. To the point that during the safavid period 200 years later persians were only 20~30% of the population. And the resistance spirt of the iranian people faded away with it.

As turkic militant tribes. moved from anatolia to azerbaijan ( the one in iran) iranian ones were getting fed to the steppe meat grinder.

Sunni iran is a tale of wasted potential and bad luck.

In the words of khayyam e nishapuri :

“I saw a bird perched on the walls of Tus, Before him lay the skull of Kay Kavus, And thus he spoke: “alas! alas!” Thy drums are hushed, thy larums have rung truce”