The outer courtyard formed a buffer zone (a space that protects another space) around the holy things in the inner courtyard. This open area separated common space from the most sacred space. In this way, it helped guard what was holy.
Thirty rooms were built along the walls of the outer courtyard. The text does not clearly state the purpose of these rooms. It also does not give their exact measurements. This lack of detail increases the contrast between the less important outer area and the central holy space, which receives much more attention.
These rooms were most likely used by the Levites. The Levites were members of the tribe of Levi who served in temple worship. They probably used these rooms for different tasks related to their service.