The Treaty of Nerchinsk: A treaty between Russia and China that was written in Latin

The Treaty of Nerchinsk between Russia and China, which was signed in 1689 at the Russian fort of Nerchinsk near the Amur River, opened up trade between the two countries and established a border to be marked with boundary stones. As no one in the Russian and Chinese delegations could speak both languages, the main negotiators were Andrei Bieobocki of Poland for Russia and the Jesuit missionaries Jean-Francois Gerbillon of France and Thomas Pereira of Portugal for China. They spoke Latin to each other and translated back and forth into Russian and Chinese for their respective delegations. So the treaty was ultimately written in Latin rather than in Russian and Chinese. (Andrew Shields, #111words, 13 January 2023)