Hallownest was a really advanced civilization if we look closely. Besides there are a few things of them that seem to be more medieval (like the fact that the city guardians use nails and spears to attack), there are other that show us that the pale king's empire had advanced technology. One of the most compelling evidences that we see of this is in crystal peak. We can notice, all over the area, different types of machines and mechanisms such as conveyor belts, rock compressors, and laser beams (though the latter might perhaps just be a natural property of the crystals themselves).
And when arriving to the end of the zone, we discover a kind of workshop with some huge robots in it. If we read the description of the crystal heart, we can see that these very robots are, in fact, creations of the inhabitants of Hallownest, used for mining.
Hallownest was a very technologycal developed civilization, and I would even go so far as to say that these mining golems could rival the Chorus of Pharloom.