Short answers, pulled from the story.
The Behistun Inscription was carved during the reign of King Darius I between 522 and 486 BC. It stands as the oldest known text written in Old Persian and marks the beginning of a three-millennium linguistic lineage.
Iranian Persian serves as the standard variety spoken within Iran, while Dari functions as the official language of Afghanistan since 1964. Tajik represents the third major standard, designated officially by that name in 1999 for use in Tajikistan and Uzbekistan.
Ferdowsi composed the Shahnameh during the tenth century to preserve Persian culture after the Arab conquest. The Samanid Empire supported early New Persian literature between 874 and 999 CE, fostering a golden age of poetic production.
Persian served as a trans-regional lingua franca across Greater Persia and much of South Asia until at least the nineteenth century. The Ottoman Empire adopted Persian as its official court language, and Mughal emperors made Persian the sole official language of their Indian subcontinent empire for five centuries prior to British colonization.
The Academy of Iran was established in May 1935 to lead campaigns replacing foreign loanwords with native terms during the twentieth century. Tajiki uses Cyrillic script instead, a change implemented under Soviet rule in the late 1930s.