The East Country means the land of sunrise. Together with the country of sunset, it poetically represents the whole earth.
Definition
The East Country literally means the country of sunrise. It is a poetic geographical expression set against the country of sunset.
Biblical Usage
The East Country is mentioned together with the country of sunset as a way of expressing the whole earth.
Historical Bible Dictionaries
International Standard Bible Encyclopedia (ISBE)
<p>kun'-tri ('erets mizrach):</p><p>Lit. "country of the sunrise" over against the "country of the sunset" (Zec 8:7). The two together form a poetical expression indicating the whole earth.</p>