Numbers 2:18-23

‘On the west side shall be the standard of the camp of Ephraim according to their hosts, and the prince of the children of Ephraim shall be Elishama the son of Ammihud. And his host, and those who were numbered of them, were forty thousand and five hundred. And next to him shall be the tribe of Manasseh, and the prince of the children of Manasseh shall be Gamaliel the son of Pedahzur. And his host, and those who were numbered of them, were thirty and two thousand and two hundred. And the tribe of Benjamin, and the prince of the children of Benjamin shall be Abidan the son of Gideoni. And his host, and those who were numbered of them, were thirty and five thousand and four hundred.'

When encamped the Rachel tribes, with their weaker numbers, would protect the west. This was probably seen as the least dangerous side. On the march they would follow the Dwellingplace. Once again full details are given of them.