that sounds like a great step, looking forward to it :)
Yeah I know it would restrict the production. But wouldnt it be more challenging to start with wooden buildings as it represents an easy start and to achieve Mudbricks as a higher "tech" or wealth level? I was a bit bored so I checked the web to get an answer how common mudbricks were. And depending on location it was not the most usual construction material.
Egypt for example had depending on the area wood or mud but as a high level stone buildings.
But Babylon had only wood and mud, Stone was not so interesting for them.
Will the river be open for trading routes later on? like an alternative for roads? ;)