>>63943454
Well equipped solders started to add various reinforcements on top of their mail in the 13th century (with perhaps some examples even earlier). Note how the Danish/German soldier in >>63943258 wears a mail hauberk underneath his CoP.
A for the coat of plates itself it's really a 14th century thing, with the 15th and 16th century stuff being brigandine instead, ie the CoP's direct descendant.