Songjiang is a suburban district (formerly a county) of Shanghai. It has a land area of 605.64 km² (233.84 sq mi) and a population of 1,909,713 (2020). Owing to a long history, Songjiang is known as the cultural root of Shanghai.

Songjiang Town, the urban center of the district, was formerly the major city in the area. It is now connected to downtown Shanghai by Line 9 of the Shanghai Metro.

The prehistoric coastline of the East China Sea was much farther inland, at Xinzhuang near Songjiang's current eastern border with Minhang District. It was only gradually that silt from the Yangtze River filled in downtown Shanghai about 2000 years ago and then Pudong and Chongming Island over the last 1000 years.

Modern archaeology has established a chronology of the main cultural groups who lived in the present area of Songjiang District in Neolithic China: the Majiabang in the 5th millennium BC), the Songze in the 4th millennium BC), and the Liangzhu in the 3rd millennium BC. The Majiabang were among the first harvesters of rice and kept domesticated pigs while still frequently hunting deer. The Liangzhu possessed a high stratified society that almost certainly represented one of the earliest states in East Asia. The Liangzhu site at Guangfulin in Songjiang has been developed into Guangfulin Relics Park, an expansive museum and tourist attraction.

Traditional Chinese historiography only recorded these people as among the Baiyue—the "Numerous Southern Barbarians"—until the growth of the siniticized Wu Kingdom at Suzhou in the 1st millennium BC. During the Spring and Autumn period at the end of the Zhou and under the Warring States, the area of present-day Songjiang passed from Wu to Yue to Chu before the unification of China under Shi Huangdi of Qin in the 3rd century BC.

In the Three Kingdoms period that followed the end of the Han in the 3rd century AD, Sun Quan's Wu Kingdom helped develop and further signify the area. Another boost came from the completion of the Grand Canal under the Sui, linking Songjiang with Hangzhou, Shaoxing, and Ningbo in the south and Suzhou, Luoyang, Xi'an, and Beijing in the north. By the mid-Tang, the region had developed enough that it was organized in 751 into Huating County, the first county-level administration within modern-day Shanghai.

In the 1250s at the end of the Southern Song, the 10-year-old Songjiangese girl Huang Daopo fled her hometown and an arranged marriage to live with the Hlai on Hainan. She returned around 1295 with new strains of cotton, an early cotton gin, and other advances to cotton cultivation and processing that made the sandy lands of eastern Huating County so much more prosperous that Huang was later deified out of gratitude. By the mid-Qing, as much as ¾ of Songjiang's farmland was devoted to cotton. Under the Yuan, this new wealth saw Huating elevated to prefectural status and renamed Songjiangfu. This is sometimes considered the origin of China's modern textile industry. It was also under the Yuan that the city first had enough Hui to establish Shanghai's first mosque.

In 1404, headwaters previously emptying into the Wusong were rerouted by local officials, diminishing the size of Suzhou Creek and expanding the Huangpu River to its modern importance. Songjiang was better fortified under the Ming in response to attacks by the Japanese "Wokou" pirates, who sometimes raided and sometimes occupied to the town. The Ming also saw the Jesuits—who counted the influential Shanghainese official Xu Guangqi among their converts—establish the town's first known church. Owing to the importance of Portuguese and Latin at the time, the town's name was romanized Sumkiam.