Sary-Aka's embassy (Russian: Посольство Сарайки) was a mission from the commander of the Blue Horde Mamai sent to Russian Eastern border province of Nizhny Novgorod in 1374 to undermine the influence of the Prince of Moscow in his struggle for supremacy among the Russian provinces and due to his open opposition to Mongol authority in Russia. The embassy was ambushed and the survivors were imprisoned in the wooden fort of Nizhny Novgorod until the 31st of March 1375 when Sary-Aka with the rest of Tatars were massacred by Russians.