White, Beginner’s Greek Book, §72.I.5:
τὴν ἱερὰν χώραν ἁρπάζεις ἐκ θαλάττης εἰς θάλατταν.
How should I render it? “You seize the land from one sea to another”? So weird… Could you please explain what the author really meant? Thank you.
‘From sea to sea’ doesn’t strike me as a particularly weird expression. But perhaps I’ve heard the song “America the Beautiful” a few times too often. 
You might want to take at look here:
http://www.phrases.org.uk/meanings/from%20sea%20to%20shining%20sea.html