During the Song Dynasty, the Grand Canal played a pivotal role in facilitating transportation and economic development rather than serving primarily as a barrier or aiding irrigation directly.
It served as a vital trade route, enhancing commerce by linking northern and southern China. The canal enabled easier, cheaper, and more efficient transportation of goods, including rice, between the agriculturally rich regions.
This not only facilitated economic growth but also contributed to cultural exchange and governmental control over the vast empire.
While it indirectly supported agriculture through trade and transportation, its primary function lay in enhancing trade and communication rather than directly aiding irrigation or defense.