The Romans relied on Egypt for several reasons, primarily because of its rich agricultural resources and strategic location. Egypt was known as the "breadbasket of Rome" due to its vast fertile lands, which produced a surplus of grain and other crops that could be exported to other parts of the empire. In fact, Egypt was the largest supplier of grain to the Roman Empire, which was crucial to feeding its growing population.
Additionally, Egypt's location at the crossroads of major trade routes made it an important hub for commerce and transportation. The Nile River provided a convenient waterway for goods to be transported both within Egypt and to other parts of the empire. This made Egypt a vital center for trade, not only for the Romans but for other civilizations throughout history.
Finally, Egypt's cultural and religious significance also made it an important ally and source of legitimacy for the Roman Empire. The Romans were known for adopting and incorporating aspects of local cultures into their own, and Egypt's ancient civilization and rich mythology made it an appealing source of inspiration for Roman art, architecture, and religion. The Romans also relied on the support of the Egyptian elite, who were often integrated into the Roman administration and helped to maintain order in the province.