I remember reading in Gates of Fire [0] that the Spartans used heavy, round oak shields which suited there phalanx style of warfare.

The Persians (and their allies) used wicker shields that chose light weight over protection [1].

More recently, there was also a video floating around recently of how protesters were building Viking shield walls to protect themselves [2]

0 - https://amzn.to/39n23Jx 1 - https://en.wikipedia.org/wiki/Sparabara 2 - https://twitter.com/joshuapotash/status/1291962889323020288?...