Timur preferred to fight his battles in the spring. However, he died en route during an uncharacteristic winter campaign. In December 1404, Timur began military campaigns against Ming China and detained a Ming envoy. He suffered illness while encamped on the farther side of the Syr Daria and died at Farab on 17 February 1405, before ever reaching the Chinese border. After his death the Ming envoys such as Fu An and the remaining entourage were released by his grandson Khalil Sultan.