Here are some Sumerian spearmen of Lagash, that date to c.2500 BC, a mix of figures from Eureka, Castaway Arts and Warlord/Cutting Edge. The appearance of these is based on the Vulture Stele, see the article, photos and line drawings of this on the Sumerian Shakespeare website. The spearmen of Ur with their distinctive capes with copper discs are based on the Standard of Ur and date to c.2600 BC. According to the Stillman & Tallis WRG book, Armies and Enemies of the Ancient Near East 3,000 BC to 539 BC 'the large, flat rectangular Sumerian shield, first illustrated on the 'Vulture Stela', probably hastened the abandonment of the protective cape. Made of dyed oxhide and having nine (not six as often stated) round, copper bosses on its face, each shield is shown as being carried by a special shieldbearer standing to the left of each spearman on the stela' (p.122 ).
I have my Lagash units based with shield bearers in the front rank with rear ranks of spearmen, their spears projecting over the shield bearers. Interpretations of their appearance and how they fought are tricky, a lot of figure manufacturers have spearmen with capes, spear and shield and others with spear and shield. Some have six bosses rather than nine on the shields (Museum Miniatures and CP Models). There are a lot of nice Sumerian ranges available now with 15mm (Chariot Miniatures, Essex Miniatures, Eureka Miniatures and Museum Miniatures) and 28mm ( Wargames Foundry, Warlord/Cutting Edge, CP Models, Eureka Miniatures and Newline Designs). Interestingly the Museum Miniatures 15mm range, and the CP Models 28mm range are the same figures, by the Z sculptor but different scales.