I have a cube with 47526 vertices, and upon importing it, the mesh gets split into 2 meshs. Is there a way to prevent unity from doing so?
You’re probably exceeding the 64k vertex limit per mesh.
Now, your cube may not look like it does exceed the limit, but keep in mind that every smoothing group and every UV seam produces double vertices and your 3D programm may not show the right numbers there.