Radak citing Ibn Ezra: From the southern sea (Yam Suf) until Yam ha'Gadol (Mediterranean Sea) in the west of Eretz Yisrael, together with "umi'Tzafon v'Ad Mizrach" these are all four directions. Nichush is not found in Eretz Yisrael - all the more so in Chutz la'Aretz and in the days of Galus.

Malbim: People will go from the southern sea to the western sea, and from north to east - all four directions. In all the places that they will go in Galus, they will seek Devar Hashem, and not find it. After the Churban, also the Bas Kol and appearance of Devar Hashem ceased.