Why was Kaifeng the first Chinese capital mainly known as a commercial metropolis?

Kaifeng’s status as the first Chinese capital primarily known as a commercial metropolis was driven by its strategic role as a major transportation and economic hub. Its rise to prominence was fundamentally linked to the Grand Canal, which connected the Huang He with the Huai River, the Yangtze River, and the region of Hangzhou.1

As the junction for four major canals, the city became a central conduit for vast volumes of private shipping and tax revenues in the form of grain and other commodities. This logistical advantage fostered a thriving industrial complex, including a significant iron industry, which supported a large urban population estimated at 600,000 to 700,000 during the 11th century. Under the Song dynasty, this concentration of trade and industry established Kaifeng as the most important commercial center in East Asia.1