Why did the Romans call the cuirass "muscular"? Ancient Greeks in the 5th century BC thought of making the surface of the cuirass not smooth, but repeating the relief of human muscles. "Lorica" means "armor", and the word "muscle" does not need translation.
The cuirass was called by the Romans "lorica musculata". From that time on, the cuirass became the hallmark of Roman commanders who could afford custom-made armor. Subsequently, already under the Empire, armor began to be purchased and supplied to the troops on a centralized basis, of standard sizes and quality. While chain mail or plate armor (lorica segmental) could be adjusted in size and repaired in field conditions. The cuirass had to be adjusted to the height and physique, which required an experienced blacksmith. Cuirasses were very expensive, and in Republican Rome, legionnaires bought armor and weapons at their own expense. Why did the cuirass cease to be the main Roman armor? There were good reasons for this. And it remained so for only about a century. The cuirass became a widespread version of Roman armor only in the 2nd century. But at first they did not have the means to provide most of the legionnaires with cuirass. Solid armor of two bent metal plates, covering the body, but leaving the limbs free, was used by all ancient peoples. But this invention immediately became popular and spread throughout the Mediterranean. It is not known who exactly came up with the first cuirass. The formation of the enemy phalanx, bristling with spears, forced to look for a method of protection, combining the strength of a solid plate of metal with the mobility of a person in light armor. But the main armament of the infantry at that time was long spears. Flexible armor, including later chain mail, did not hold the thrust well. But even without protection, the soldiers of the Bronze Age did not want to remain. Such solid armor limited the freedom of movement of the warrior. The weight of this armor was 16-17 kg - less than that of knightly armor. It did not look very aesthetically pleasing, but at the same time it provided the owner with excellent protection from all types of weapons.
One of the oldest armor found by archaeologists is the full armor of a warrior from the Dendra necropolis, located next to the Mycenaean acropolis of Midea.
Solid metal armor appeared when people learned how to mine and process metals.