In the Yeongnam region near the Nakdonggang River, Iron Age cultures of the Proto–Three Kingdoms buried light grayish, soft stoneware vessels in tombs furnished with wooden coffins. Direct ties with Chinese commanderies such as Nangnang (Chinese Lelang) in northern Korea during this period brought Chinese ceramic-making technology and improvements in firing techniques that permitted the production of soft stoneware, known as wajil, and true high-fired stoneware, called yonjil. Wajil pottery has a grayish appearance and was fired in closed climbing-kilns, which facilitated attaining higher temperatures than open kilns could achieve. Wajil pottery includes long-necked jars with horn-shaped handles and other round-bottomed vessels, such as reddish earthenware jars, with surface decoration of straw cord impressions and incised designs in striated or lattice patterns.