(via) This short film goes down a rabbit hole to detail why so many countries end with the suffix “stan”.
Short answer: it’s the Persian word for country, derived from the root ‘-sta,’ meaning ‘to stand.’ A -stan is, literally, a place where a specific people lives. Turkmens stand in Turmenistan; Kyrgyz stand in Kyrgyzstan. Iranian languages have been using ‘-stan’ for millennia—here it is in an inscription of Xerxes—and Persian influence on neighboring languages explains why all seven sovereign -stans are contiguous with Iran. Iran itself has five -stans as provinces and its word for province is ‘ostan.’ But the term’s origin long predates written language, let alone modern nations. So there are many more -stans than these, including administrative regions, active independence movements, and historical regions. ‘st(h)?n’ meant place over 4,000 years ago in Proto-Indo-Iranian, the branch of Indo-European ancestral to both Old Persian and Sanskrit. So the Indian stateof Rajasthan, ‘land of kings,’ is a -stan too. The word especially spread north, to Armenia and to Turkestan, the land of the Turks. All of this vast area of Eurasia could be considered ‘Stanistan,’ the land where the lands are called ‘-stan.’