湖北黃陂盤龍城遺址的出土，突破過往認為商人勢力僅及於淮水流域之定見。其後隨著考古資料的增加，人們所認知的商代疆域逐步南進西拓，成為跨江南北的廣闊區域。考古資料所反映之商代「南土」文化，雖然稍事補齊文字資料的缺環，但是殷商政權能否統領文化組成紛雜的江漢─洞庭湖區，甚至深入江南，直達傳統文獻中「前交趾」的商土「四至」範圍，則為進一步討論的重點。因此本文於討論中，將殷商政權發展以都邑位置畫分為前、後兩期，考量兩大時段內的「南土」文化變遷，理解「南土」空間範圍的變遷，探討商人南進模式，試圖由此分析商代政權的政治結構。本文認為商代前期，殷商政權掌控的「南土」，包括有漢水以東與長江沿岸的零星據點，至於漢水以西與湘西澧水流域則應屬商文化影響區，而非商人所能掌握之地。商代後期，商文化向外發展幅度明顯縮減，不過，黃河與長江流域之間的交流仍持續進行。盤龍城作為商族南土封地核心，其興廢取決於商王政策；而由本土族群所建立的吳城，則是向殷墟進行資源交換的地方政體。本文亦認為殷商政體的權力擴張，並不專以索求資源為導向，「南進掠銅」之說，無法完整解釋商人經營「南土」的原因。

The Panlongcheng site in Hubei is the first site of Shang discovered in the middle Yangzi River valley. This discovery has overturned the taken-for-granted hypothesis that south part of Shang's territory, 'Nan Tu'(南土) had established in the Huai River, and Shang culture had never expanded across the Yangzi River. This paper mainly has a survey of the spread of Shang culture in south region. By analyzing the variation of 'Nan Tu', we can comprehend the details of culture intercourse, and it can be regarded as the framework of political structural system of Shang. According to the capital of Shang, discussion is divide into two parts, the former (the Erligang culture) and the later (the Yinxu culture) stage of Shang.Systematic researches on related archaeological data from the Shang period, and comparative studies of them with literal records have showed the structural system of 'Nan Tu'. In the period of the Erligang culture, east part of Jiang-Han Plain and the bank of the Yangzi River are all territories of Shang with varying local autonomy. But the culture expansion from Central Plains has declined after the first phase of the Yinxu culture, expander of Shang seems to be catching the wave. Panlongcheng site was ruined after the second phase of the Upper Erligang culture. Local culture has progressed in state of the art, and emerged independent character. Wucheng culture in the area of Poyang Lake flourished in Yinxu period, and became the development force at the core. Shang culture is no longer hegemonic, but still held sphere of influence in the middle Yangzi River valley.