 The Bulgar state had been weakened by these conquests.During the mopping-up operations of the Mongols on the Dnieper, a messenger arrived from the Great Khan ordering Subutai and Jebe to return to the Volga River, locate Jochi, and return with him to Mongolia.According to historian John Chambers, ""The delayed arrival of the reinforcements which were at last advancing towards the Volga and the absence of Jochi from a preliminary briefing with his father had not been due to illness.