The late January snow settled sporadically along the Xiangjiang River's banks, draping the ancient gray tiles of Tongguan Old Street with a gentle dusting of frost.

Ceramics have been woven into the very fabric of this winding lane in Wangcheng district, Hunan's provincial capital, Changsha, that took shape during the Tang Dynasty (618-907), from walls of stacked pots and murals inlaid with porcelain shards to the towering kiln chimney.

The view from Yunmu Mountain, beside the old street, reveals Tongguan's millennial secrets: the ancient town to the north, the farmlands to the south, the flowing Xiangjiang to the west, and river islets scattered throughout.

This is the "mountain-water-isle-polder" natural formation, the precise geographical endowment that nurtured the birthplace of the world's underglazed polychrome porcelain 1,200 years ago, says Chen Kuang, an official in charge of cultural affairs with Wangcheng district.

"Water was the lifeline of ceramics," Chen says. "Sheltered by mountains on three sides and facing water on the other, this was a major production and transit hub for porcelain in the Tang era."

Between the Tongguan kilns and the Xiangjiang sits Shizhu Lake, from where finished wares embarked on their journey, connecting the Yangtze River and the coast, and eventually traveling across the seas as key commodities on the Maritime Silk Road.

According to the Northern Wei Dynasty (386-534) geology record, Commentary on the Waterways Classic, Yunmu Mountain's soil is suitable for pottery, and over a thousand households of potters lived along the river.