Lander Talmid
The Gemara in Nedarim (58a) tells us that in order for the Shechina to rest on someone, he must have four attributes; he must be wise, rich, strong, and modest. The Kli Yakar says that grouping of the encampment of Bnei Yisroel into four Degalim was to highlight these four attributes of Klal Yisroel. so that the Shechina would rest on us.
All four Degalim surrounded the Mishkan because these attributes were used only to serve Hashem and bring the Shechina down to Klal Yisroel..
From Revach.net