Blender Map Segmentation Into Quarters

I have a large city-scale map sitting in Blender that has grown too heavy to manage in a single file. I need it split cleanly into four separate .blend files, each weighing in at roughly 20 MB so they remain lightweight for future edits and exports.

Here’s what matters:
• Source content: a city map—no topographic or fantasy elements involved.
• Target fidelity: medium detail is perfect; I’m not chasing ultra-high realism, but I don’t want it overly decimated either.
• File sizing: each of the four output files should hover around 20 MB, keeping textures and geometry balanced so none of them balloon past that figure.

If you have a reliable workflow for slicing large scenes in Blender—collections, linked libraries, or any other method—and can preserve materials and UVs intact, you’re exactly who I need. Let me know how you plan to tackle the split and how quickly you can turn this around, and I’ll get the master file over to you right away.