Question How does unity order sub meshes from fbx?

Hey, we're having some issues with sub meshes being imported in incorrect order from an fbx exported from Maya.

Anyone know how Unity orders sub meshes? Is it based on the material index/order?
Wondering how to get a group of faces with "material1" always import as submesh = 0, and "material2" always import as submesh=1

This doesn't seem to be the case, unless something is wrong with our Maya scene.