Sary-Aka's embassy was dispatched by Mamai, a military commander of the Blue Horde, which ruled over lands in what is now the southern Ukrainian steppes and the Crimean Peninsula, to Nizhny Novgorod in 1374.
To secure the safety of the meeting the eldest son of Dmitri Konstantinovich of Suzdal, Vasiliy Kirdyapa, was ordered to dispatch an armed force to Nizhny Novgorod to take the surviving members of Sary-Aka's embassy and disarm them on 31 March 1375.
Sary-Aka either anticipated the threat or was warned in advance so he ordered the captured Tatar battlers to break out of the prison located next to the Dmitrovskaya Tower and occupy the courtyard of the local bishop nearby.
Apart from the latter's son some later sources mention Alexius, Metropolitan of Moscow who forced his subordinate Dionysius to initiate the killing in an attempt to spark Mamai's revenge and therefore consolidate the Russian warlords.
Whatever the actual reason was, all the Russian principalities submitted to the Prince of Moscow, including Ryazan and Nizhny Novgorod, although Tver continued its struggle for the supremacy.