Charles Ellicott Commentary Revelation 21:12-13

"having a wall great and high; having twelve gates, and at the gates twelve angels; and names written thereon, which are [the names] of the twelve tribes of the children of Israel: on the east were three gates; and on the north three gates; and on the south three gates; and on the west three gates." — Revelation 21:12-13 (ASV)

And had a wall great and high...—Or, better (as the construction is continued), Having a wall great and high, and having twelve gate-towers, and at the gate-towers twelve angels, and names inscribed, which are the names of the twelve tribes of the sons of Israel: from the sun-rising (that is, facing east) three gate-towers; from the north three gate-towers; from the south three gate-towers; from the sun-setting three gate-towers.

On this arrangement of gates, Numbers 2, Ezekiel 48, and Revelation 7 should be compared. In the encampment in the wilderness (Numbers 2), the tribes were arranged as follows: on the east, Judah, Issachar, Zebulun; on the south, Reuben, Simeon, Gad; on the west, Ephraim, Manasseh, Benjamin; on the north, Dan, Asher, Naphtali. There is perhaps an allusion in the present passage to this wilderness encampment, and to the readjustment of the order of the tribes in Ezekiel (Ezekiel 48); but there is more than order here: the gates lie open to all quarters; there is no refusal of admission to any people.

The representatives of all nations, and kindreds, and people, and tongues, are (Revelation 7:9) in the city of Christ; in Him there is neither barbarian, Scythian, bond nor free, but all are one. The diversities of human nationality and character, of age and race, and climate, are brought into one communion and fellowship. (Compare Note on Revelation 7:4.) The wall great and high is mentioned to assure us of the security and peace of that city where no foe ‘or thief approacheth’ (Isaiah 26:1; Zechariah 2:5).