By 1218, as a result of defeat of Qara Khitai, the Mongol Empire and its control extended as far west as Lake Balkhash, which bordered the Khwarezmia (Khwarezmid Empire), a Muslim state that reached the Caspian Sea to the west and Persian Gulf and the Arabian Sea to the south.
How far west did the Mongol Empire extend after Kuchlug's demise?
Lake Balkhash