Complex sentence: The Aztecs did not initially adopt metal working (even if they had acquired metal objects) however as conquest gained them metal working regions the technology started to spread and by the time of the Spanish conquest a blooming bronze smelting technology seemed to be nascent.
Split into simpler sentences: The Aztecs did not initially adopt metal working (even if they had acquired metal objects). By the time of the Spanish conquest, a blooming bronze smelting technology seemed to be nascent.