before computers, photo manipulation was achieved by retouching with ink, paint, double-exposure, piecing photos of negatives together in the darkroom, of scratching Polaroids.
Airbrushes were also used, whence the term "airbrushing" for manipulation.
Darkroom manipulations are sometimes regarded as traditional art rather than job related skill.
In the early days of photography, the use of technology was not as advanced and efficient as it is now.
Results are similar to digital manipulation but they are harder to create.