Logically, it would make more sense for the chinks to put their capital in the south. The south is economically much richer than the north. Also, the capital in the south provides a buffer zone from the barbaric tartars in the north and is also nearer the trading routes of south east asia.
However, historically, chink emperors and warlords who put the capital in the south always ended up being overrun by people of the North.
Nanjing (known as Jianye) served as capital of Eastern Wu during the 3 Kingdoms. Overrun by Wei/Jin from the North.
Southern Sung, despite being even richer than Northern Sung, was overrun by the Mongols.
The Ming Dynasty's original capital was in Nanjing. The 2nd Ming Emperor was eventually overthrown by his uncle, whose base was in Beijing.
The Southern Ming dynasty was also overrun by the Qing from the north.
The Taiping rebellion, whose capital was in Nanjing, was also overrun by the Qing, whose capital was in Beijing.
The KMT, again based in Nanjing, lost their capital to the Japs during WW2 and later on, lost the civil war to the commies, who were based in the North.
In many cases, rich and powerful dynasties operating from richer southern capitals, all lost to poorer and leaner enemies from the north. It's bad luck to put one's capital in Nanjing. Beijing has far better fengshui.