The Posuk says: וְשָׂא עֵינֶיךָ יָמָּה וְצָפֹנָה וְתֵימָנָה וּמִזְרָחָה וּרְאֵה בְעֵינֶיךָ The question is Moshe is standing in Chutz Laretz why look back thats not Eretz Yisroel that is also Chutz Lareatz why did Hashem tell him to look Back?
A more mussar-dik answer: perhaps we can only really know where we are going when we know where we came from. Note also that mizrach is last, suggesting that, while one must remember where he came from, the real essence is where he is going.
The cantillation notes break the directions into pairs: "West-and-North", and "South-and-East."
If I understand correctly, Moses is standing approximately across the Jordan River from Jericho. If he looks West, he sees the Promised Land. Same if he looks North, according to the Biblical cartographers who have the Biblical northern border jutting east near the Galilee (consult a map, there's one in the Stone Chumash; I don't remember if this is Kaftor VaFerach or Tevuos Ha'aretz's opinion).
If Moses then pauses and looks South and East, he'll see the Transjordan portions that he did already get to see, which he was able to turn into quasi-Israel.
What to make of this lesson-wise, probably something like what Jeremy is saying. I apologize for cannibalizing your answer, but this was too complicated to fit in a comment.
The Sifri says that when Moshiach will come Eretz Yisroel will spread out into Chutz Laaretz so Hashem is telling him look back that will one day be Eretz Yisroel too.