Treaty of Nerchinsk (1689)

The first ever treaty entered into by China with a foreign power was the Treaty of Nerchinsk, in 1689, which settled territorial issues in Siberia and Outer Manchuria with the Russian Empire.

This treaty was never deemed to be 'unequal',  because Qing China, then under the rule of the Kangxi Emperor, was is the ascendant and Russia acquiesced to Chinese wishes.

The breathing space thus created on the northeastern flank enabled Manchu expansion into the northwestern regions, culminating in 1757 with the Qianlong Emperor's conquest of Dzungaria or Eastern Turkestan, immediately thereafter renamed Xinjiang, literally 'New Frontier'.

Below is a map of the Sino-Russian border as defined by the Treaty of Nerchinsk.