Final answer:
One similarity is that both states and rulers established monopolies and promoted safe trade routes to enhance trade, generate revenue, and secure the flow of goods during the period 1200-1450.
Step-by-step explanation:
One similarity in how states and rulers fostered and promoted trade and exchanges during the period 1200-1450 is through monopolies and fostering safety of trade routes. States often granted or sold exclusive trading rights, setting up territorial or commodity-based monopolies. This not only provided a source of revenue for rulers, as with European trading companies in East Asia, but also motivated these companies to maintain and enhance the security of trade routes for a stable flow of goods.
Additionally, the rise of financial structures such as governments issuing debt, the use of banks, and joint stock companies facilitated trade. For example, in Italy, city-states created a robust commercial infrastructure, doubling as political powerhouses and significantly enhancing the safety and predictability of the trading environment, promoting trade expansion.