Where does “ইণ্ডোনেচিয়া” come from?

ইণ্ডোনেচিয়া (Assamese) comes from English Indonesia, from Ancient Greek νῆσος — island.

Ancestry of “ইণ্ডোনেচিয়া”, step by step

Step	Language	Word	Meaning
1	English	Indonesia	—
2	Ancient Greek	νῆσος	island