One of the reasons why states from a federation is to

The reason why states form a federation is to cater for local differences. A federation is a system of government where power is shared between a central government and individual states. By doing so, each state can have some degree of autonomy and can make decisions based on their unique needs and circumstances. This allows for a more tailored approach to governance, rather than a one-size-fits-all approach that may not work for all regions of a country. Additionally, a federation can provide a mechanism for smaller states to have a greater say in national affairs and can help to prevent the concentration of power in a single location.