Why is austria named austria?

Firstly in German the country is called "Österreich". At first the country was denoted as "Marchia Orientalis", wich means something like "eastern border".
The first German translation was "Osterrîchi"; a term, which first appeared in the Ostarrîchi Document from 996.
The word"Austria" is a latinization of the German "Österreich".

An other translation of "Marchia Orientalis", was "Ostmark", this name for Austria was used by Nazi Germany