The Parthians, in About Twenty Lines
اشکانیان
Nearly five centuries of history. Ferdowsi says he cannot find anything to say about it.
No openly licensed painting of this scene sourced yet.
After Alexander, the Parthians rule Iran for something close to five hundred years. They fight Rome to a standstill for generations and hold the plateau longer than the Sasanians will.
Ferdowsi gives them roughly twenty lines. He names a few of them, remarks that they were called the 'clan kings', says that nothing of their deeds was recorded in the sources he had, and moves on to Ardashir.
It is the single strangest gap in the poem, and it is not carelessness. It is what happens when a poet is working from Sasanian court chronicles, and the Sasanians, who overthrew the Parthians, had no interest in remembering them.
Why it matters
The best short lesson in what the Shahnameh actually is. It is not a neutral history of Iran; it is a thousand-year-old poem assembled from the records that survived, with the politics of whoever kept those records baked in. On the spine this gap is visible as a sliver, five centuries thinner than a single hunting scene.