Where does “এষ্ট'নিয়া” come from?

এষ্ট'নিয়া (Assamese) comes from English Estonia, from Medieval Latin Estonia.

Ancestry of “এষ্ট'নিয়া”, step by step

Step	Language	Word	Meaning
1	English	Estonia	—
2	Medieval Latin	Estonia	—

এষ্ট'নিয়া — Etymology, Origin & Word History | Etymology Explorer