There may have been no world language, but there were multilingual people.

For instance, when the Korean army surrendered to the Manchus following the Battle of Sarhū, negotiations were translated by a Korean interpreter who knew Manchu.

When Cortes and Motecuhzoma met in Tenochtitlan, the Spaniard's words were translated into Maya by a Spaniard who had been a Maya slave for years. Then they were translated into Nahuatl for Motecuhzoma by La Malinche, a native woman. Vice versa when Motecuhzoma spoke.

There were and are regional lingua francas. Classical Chinese was a common written language from Japan to Vietnam, so a Japanese emperor and a Vietnamese emperor would have been able to communicate simply by writing. In modern countries with great linguistic diversity, official languages often serve the same role. Then we have pidgins, often used for trade, which can develop into full-fledged languages called creoles.