Sub-Saharan Africans were among the world's pioneers in the working of metal. As early as 1000 AD, Nguni-speaking peoples had spread ironworking techniques across much of southern Africa as they migrated from the Great Lakes region.
This early African ironworking was relatively sophisticated for its time. In areas like the now Witwatersrand, it grew extensive enough to contribute to deforestation as smelters consumed hardwood to fire their open-air forges. Though production remained a small "one-man and his mate" operation, the process transformed raw iron ore and scrap into a basic low-grade steel.
Smelting utilized hand-operated bellows to feed fires fueled by bellows, heating the ore to temperatures where it could be worked with basic stone hammers. The lack of formers or techniques to control thickness meant the resulting metal was inconsistent in quality and form. But it allowed the forging of tools, spearheads, and other implements to meet basic needs.
Despite this metalworking proficiency, Sub-Saharan Africans did not develop metal armor or shields like those seen in armor-equipped warrior societies across Europe, Asia, and the Americas. The hot climate of the region, with temperatures often reaching 35-45°C, made heavy metal protection impractical for warriors who prized mobility and endurance on the battlefield.
Additionally, the nature of pre-colonial warfare, which was relatively ritualized with opponents exchanging ranged spear throws, provided little impetus for heavy anti-missile defenses. Basic leather and hide sufficed against the lightweight javelins of the era. In decisive engagements, combat inevitably moved to close quarters with short spears, clubs, and raids to burn villages - negating the need for sophisticated metal armor.
So while lack of metal shielding may seem an odd omission given their metalworking capabilities, Sub-Saharan Africans tailored their metallurgical tradition to suit their environment. Overall battlefield considerations - rather than any shortfall of knowledge - led them on a different trajectory from the armored knights and samurai require more protective metal weapons and defenses.