Mongol invasion of Rus'
In medieval European sources, the names "Merdas, Merdinis, Merdium, Mordani, Mordua, Morduinos" have appeared. In the Russian Primary Chronicle, the ethnonyms "Mordva" and "mordvichi" first appear in the 11th century. After the Mongol invasion of Rus', the name Mordvin rarely gets mentioned in Russian annals, and is only quoted after the Primary Chronicle up until the 15th–17th centuries.