Early communities were small families which by time turned to villages. Early communities consisted of 15-20 members and everybody had a job. With a small population they produced just enough food for the community. Since they needed help defending themselves and stabilizing their food situation they came together and formed villages.
Familie based communities joined together to villages because they needed help. Even though they were producing enough food most of the time, they still needed support with other tasks. With the ability to join together they would work on tasks such as stopping rivers, defend from other villages, and produce more food and material. This also put trade into more factor because of the production of more material.
During the time of empires wealth was one of the main factors. Some of the way they obtained wealth was tax. Rulers would tax people crossing with goods and would become wealthy. With wealth they would conquer neighboring cities and form empires. Another way they gained wealth was tribute. Tribute was a tax on conquered citizens that helped become even more richer. Overall, they obtained more land by becoming wealthier which lead to more wealth, land, and armies.