Archaeological excavations in the Ji'an area have unearthed several Yemaek sites along the Amnok River and its tributary the Hunjiang, which belong to the regional Neolithic and Bronze ages.[3]
After the fall of Wiman Joseon to the Han dynasty in 108 BCE, Ji'an was part of Goguryeo County under the administration of Xuantu Commandery.[3] In 3 CE, the second ruler of Goguryeo, King Yuri, moved the state's capital to Gungnae (modern Ji'an) and established the mountain fortress Hwando nearby to defend it.[3] Hwando was sacked by Wei State in 244 CE during the Goguryeo–Wei War. In 342 CE, Hwando was destroyed and thousands of people captured by the Murong Xianbei, after which Goguryeo focussed on expanding south and east. In 427 CE, the eleventh ruler of Goguryeo, King Jangsu, moved the capital to Pyongyang, which saw Gungnae relegated to subsidiary capital status.[3]
Ji'an has a monsoon-influenced humid continental climate (KöppenDwa), with long, very cold winters, and very warm, humid summers. Monthly average temperatures range from −12.1 °C (10.2 °F) in January to 23.3 °C (73.9 °F) in July, and the annual mean is 7.5 °C (45.5 °F). Though the annual total, at 917.7 mm (36.1 in), is generous, precipitation is quite low during the winter and upwards of 60% of annual rainfall occurs from June through August. The frost-free period lasts around 150 days.
Climate data for Ji'an (1991–2020 normals, extremes 1971–2010)