Early communities in West Africa were family-based comunities. They were very small with around 15-20 people and an elderly ruler. Family embers would work together to deal with certain task.
Can you help me harvest the crops?
Eventually, family-based communities grouped up into villages for protection and more help. Villages were much bigger than family-based communities with a population of usually 100-200 people. Protection was very important at that time so villages were surrounded by walls to keep them safe from wildlife and attackers. Extra help was also needed because 15-20 people wasn't enough to deal with big problems like controlling rivers.
We can help. We should also group up for protection.
We can't control this flooding river!
One discovery that changed everything was the idea of smelting iron and using iron tools. That combined with the expansion of trade is what made villages turn into large towns and cities. With the new iron tools that West Africans had, they could harvest crops much easier. The new iron tools produced a surplus of crops so villages along rivers and trading routes would began to grow into big trading cities.
Look at what I made from smelting ore. Whith this new iron tool we can harvest crops easier.
That is a great idea! We might even have a surplus that we can trade with people traveling along the river!